If I choose as a subject the clergy in Chiapas and use the obvious keyword search kw chiapas and clergy in HOLLIS I get ZERO; so I step back a bit and try kw chiapas and church and this is the result:
 
 HU INDEX: LIST OF ITEMS RETRIEVED         12 items retrieved by your search:
FIND KW CHIAPAS AND CHURCH
------------------------------------------------------------------------------
SOUTH AND MESO AMERICAN NATIVE SPIRITUALITY FROM THE CULT OF THE FEATHERED
SERPENT TO THE THEOLOGY OF LIBERATION
   1 gossen gary h/ 1993  bks
 
REFUGIOS DE LO SAGRADO RELIGIOSIDAD CONFLICTO Y RESISTENCIA ENTRE LOS ZOQUE
DE CHIAPAS
   2 aramoni calderon dolores/ 1992  bks
 
OBISPOS DE CHIAPAS
   3 aubry andres/ 1990  bks
 
RELACIONES DE LOS PUEBLOS DEL OBISPADO DE CHIAPA 1772 1774
   4 garcia vargas y rivera manuel/ 1988  bks
 
SOLDIERS OF THE VIRGIN AN ETHNOHISTORICAL ANALYSIS OF THE TZELTAL REVOLT OF 
1712 IN HIGHLAND CHIAPAS
   5 gosner kevin 1951/ 1984  bks
 
IGLESIA COLONIAL DEL PUEBLO DE OSUMACINTA CHIAPAS
   6 beristain bravo francisco/ 1982  bks
 
BOLETIN
   7 (san cristobal de las casas mexico instituto de asesoria antrop)/ 
     1981+ ser
 
HISTORIA DE LA PROVINCIA DE SAN VICENTE DE CHIAPA Y GUATEMALA DE LA ORDEN DE
PREDICADORES
   8 ximenez francisco 1666 ca 1722/ 1977  bks
 
BARTOLOME DE LAS CASAS 1474 1974 E HISTORIA DE LA IGLESIA EN AMERICA LATINA 
II ENCUENTRO LATINOAMERICANO DE CEHILA EN CHIAPAS 1974
   9 comision de estudios de historia de la iglesia en latinoamerica/ 1976  
 
PRIMERA CARTA PASTORAL
  10 luque y ayerdi miguel mariano bp of chiapas/ 1884  bks
 
OFFICIA CONCESSA DIOECESI DE CHIAPAS
  11 catholic church/ 1882  bks
 
CONSTITVCIONES DIOECESANAS DEL OBISPADO DE CHIAPPA
  12 nunez de la vega francisco 1632 1706/ 1702  bks 

So I take the time to LOOK AT the 12 items, figuring that the information contained in their records may give me some ideas for other terms, and may in fact lead me to sources directly on the 'Chiapas clergy' topic... AND will probably teach me a few other valuable lessons. I type d l to see Harvard's LONG DISPLAY:
HU LONG DISPLAY   page 1 of 5      Item 1 of 12 retrieved by your search:
FIND KW CHIAPAS AND CHURCH
------------------------------------------------------HU HOLLIS# AOY9495 /bks
      TITLE: South and Meso-American native spirituality : from the cult of
               the feathered serpent to the theology of liberation / edited
               by Gary H. Gossen in collaboration with Miguel Leon-Portilla.
     PUB. INFO: New York : Crossroad, 1993.
   DESCRIPTION: xii, 563 p. : ill. ; 25 cm.
        SERIES: World spirituality ; v. 4
 
      CONTENTS: Those made worthy by divine sacrifice : the faith of ancient
                  Mexico / Miguel Leon-Portilla -- The Mayan faith / Munro S.
                  Edmonson -- Andean religion at the time of the conquest /
                  Manuel M. Marzal -- Indians and theologians : sixteenth
                  -century Spanish theologians and their concept of the
                  indigenous soul / Elsa Cecilia Frost -- Transplanted Spanish
                  Catholicism / Manuel M. Marzal -- Aztec spirituality and
                  Nahuatized Christianity / J. Jorge Klor de Alva -- The cult 
                  of the Virgin of Guadalupe in Mexico / Louise M. Burkhart 
                  -- The Tzeltal Maya-Christian synthesis / Eugenio Maurer 
                  Avalos -- The Christian era of the Yucatec Maya / Manuel 
                  Gutierrez Estevez -- The last time the Inca came back : 
                  messianism and nationalism in the Great Rebellion of 
                  1780-1783 / Jan Szeminski -- Huichol cosmogony : how the 
                  world was destroyed by a flood and dog-woman gave birth to 
                  the human race /  Peter T. Furst.
                The faith of the real people : the Lacandon of the Chiapas 
                  rain forest / Didier Boremanse -- The Mapuche of Chile : 
                  their religious beliefs and rituals / Louis C. Faron -- A 
                  visit to a Bribri shaman / Marcos Guevara-Berger -- "I am 
                  black jaguar!" : magical spells and shamanism of the Pemon 
                  of southern Venezuela / Peter T. Furst -- On the human 
                  condition and the moral order : a testimony from the 
                  Chamula Tzotzil of Chiapas, Mexico / Gary H. Gossen -- 
                  Popular faith in Brazil / Carlos Rodrigues Brandao -- 
                  Santeria or Orisha religion : an old religion in a new 
                  world / Julio Sanchez Cardenas -- Life of the heart : a 
                  Maya Protestant spirituality / David G. Scotchmer -- 
                  Guerrilleros, political saints, and the theology
                  of liberation / Mary Christine Morkovsky.
 
         NOTES: Includes bibliographical references and indexes
          ISBN: 0824512243
 
      SUBJECTS: *S1 Indians--Religion.
                *S2 Indians--History.
                *S3 Syncretism (Religion)--Latin America.
                *S4 Latin America--Church history.
                *S5 Latin America--Social life and customs.
(This one has a LOT of useful information tucked into it, and the CONTENTS is full of interesting subjects. The SUBJECTS are Library of Congress Subject Headings, many of which will be worth doing separate SUBJECT searches at Harvard and at other libraries)
HU LONG DISPLAY   page 1 of 2      Item 2 of 12 retrieved by your search:
FIND KW CHIAPAS AND CHURCH
-----------------------------------------------------HU HOLLIS# ARO2446 /bks
        AUTHOR: Aramoni Calderon, Dolores.
         TITLE: Los refugios de lo sagrado : religiosidad, conflicto y
                  resistencia entre los zoques de Chiapas / Dolores Aramoni
                  Calderon.
       EDITION: 1. ed.
     PUB. INFO: Mexico : Consejo Nacional para la Cultura y las Artes, 1992.
   DESCRIPTION: 431 p. : map ; 21 cm.
        SERIES: Regiones
         NOTES: Includes bibliographical references.
 ACCESS NUMBER: (OCoLC)28616172
          ISBN: 9682935350
 
      SUBJECTS: *S1 Catholic Church--Mexico--Chiapas--History.
                *S2 Zoque Indians--Religion and mythology.
                *S3 Zoque Indians--Cultural assimilation.
                *S4 Indians of Mexico--Chiapas--Missions.
                *S5 Inquisition--Mexico--Chiapas.
(This one adds several significant LC Subjects --for 'chiapas clergy' it might well be *S1, but we also learn that the Inquisition was active in Chiapas, and the name of one 'tribe' (there are quite a few in Chiapas)
HU LONG DISPLAY   page 1 of 1      Item 3 of 12 retrieved by your search:
FIND KW CHIAPAS AND CHURCH
----------------------------------------------------HU HOLLIS# AKB6660 /bks
        AUTHOR: Aubry, Andres.
         TITLE: Los obispos de Chiapas / Andres Aubry.
     PUB. INFO: San Cristobal de las Casas, Chiapas, Mexico : Instituto de
                  Asesoria Antropologica para la Region Maya, 1990.
   DESCRIPTION: 106 p. : ill., maps ; 28 cm.
         NOTES: Cover title.
                "Apuntes de lectura 12-15."--Cover
 
      SUBJECTS: *S1 Catholic Church--Mexico--Chiapas--Bishops--Biography.
                *S2 Catholic Church. Diocese of Chiapas (Mexico)--History.
                *S3 Chiapas Region (Mexico)--Church history.
You don't need mucuh Spanish to know that 'obispos' is 'bishops', and in any case you could quickly guess it from *S1; *S3 looks very interesting if 'clergy' and 'church history' seem related.
HU LONG DISPLAY   page 1 of 2      Item 4 of 12 retrieved by your search:
FIND KW CHIAPAS AND CHURCH
----------------------------------------------------HU HOLLIS# AHP7024 /bks
      AUTHOR: Garcia Vargas y Rivera, Manuel.
       TITLE: Relaciones de los pueblos del Obispado de Chiapa, 1772-1774 /
                Manuel Garcia Vargas y Rivera ; introduccion, paleografia y
                notas de Jorge Lujan Munoz.
     EDITION: 1a ed.
   PUB. INFO: San Cristobal de las Casas : Patronato Fray Bartolome de las
                Casas :  Programa Cultural de las Fronteras : Instituto
                Chiapaneco de Cultura : Ayuntamiento Constitucional, 1988
 DESCRIPTION: xxii, 51 p. : ill. ; 23 cm.
       NOTES: Includes bibliographical references.
 
    SUBJECTS: *S1 Catholic Church. Diocese of Chiapas (Mexico)
This one gives another point of access via *S1 --and underlines the fact that LC Subject Headings often overlap one another, so that it's not sufficient to assume that ONE covers the subject of interest.
HU LONG DISPLAY   page 1 of 2      Item 5 of 12 retrieved by your search:
FIND KW CHIAPAS AND CHURCH
-----------------------------------------------------HU HOLLIS# ADB8061 /bks
        AUTHOR: Gosner, Kevin, 1951-
         TITLE: Soldiers of the virgin [microform] : an ethnohistorical 
                  analysis of the Tzeltal Revolt of 1712 in Highland Chiapas 
                  / Kevin Marlin Gosner.
     PUB. INFO: 1984.
   DESCRIPTION: vii, 265 leaves : ill., maps.
         NOTES: Includes index.
                Thesis (Ph. D.)--University of Pennsylvania, 1984
                Bibliography: leaves 251-261.
 
      SUBJECTS: *S1 Church and state--Mexico--History--18th century.
                *S2 Chiapanec Indians.
Again *S1 gives us another point of view, emphasizing the sacred/secular dimension
HU LONG DISPLAY   page 1 of 2      Item 6 of 12 retrieved by your search:
FIND KW CHIAPAS AND CHURCH
----------------------------------------------------HU HOLLIS# AFM5266 /bks
        AUTHOR: Beristain Bravo, Francisco.
         TITLE: La iglesia colonial del pueblo de Osumacinta, Chiapas /
                  Francisco Beristain Bravo.
     PUB. INFO: Mexico, D.F. : [s.n.], 1982.
   DESCRIPTION: iii, 113 leaves, [61] leaves of plates (some folded) : 
                  ill. ; 28 cm.
         NOTES: Thesis (doctoral)--Escuela Nacional de Antropologia e 
                  Historia, 1982.
                Bibliography: leaves 100-110.
 
  SUBJECTS: *S1 Catholic Church--Mexico--Osumacinta--History--16th century.
            *S2 Catholic Church--Mexico--Osumacinta--History--17th century.
            *S3 Osumacinta (Mexico)
            *S4 Mexico--Church history--16th century.
            *S5 Mexico--Church history.

HU LONG DISPLAY   page 1 of 2      Item 7 of 12 retrieved by your search:
FIND KW CHIAPAS AND CHURCH
----------------------------------------------------HU HOLLIS# AKT6846 /ser
         TITLE: [Boletin (Archivo Historico Diocesano (San Cristobal de las
                  Casas, Mexico))]
                Boletin / Archivo Historico Diocesano.
     PUB. INFO: 1-
                San Cristobal de Las Casas, Mexico : Instituto de Asesoria
                  Antropologica para la Region Maya, 1981-
   DESCRIPTION: v. : ill., maps ; 21 x 28 cm.
     FREQUENCY: Six no. a year
         NOTES: Vol. for junio 1988 is a reissue of vol. 1, boletin # 6 
                  (1983) which was never published.
                Title varies slightly: vol. 1, no. 6-   Boletin del Archivo
                  Historico Diocesano.
 
      SUBJECTS: *S1 Catholic Church--Mexico--History--Periodicals.
                *S2 Christianity--Mexico--Periodicals.
                *S3 Religious intitutions--Mexico--Periodicals.
                *S4 Chiapas (Mexico)--Church history--Sources--Periodicals.
                *S5 Chiapas (Mexico)--History--Sources--Periodicals.

HU LONG DISPLAY   page 1 of 2      Item 8 of 12 retrieved by your search:
FIND KW CHIAPAS AND CHURCH
----------------------------------------------------HU HOLLIS# AFH1681 /bks
        AUTHOR: Ximenez, Francisco, 1666-ca. 1722.
         TITLE: Historia de la provincia de San Vicente de Chiapa y 
                  Guatemala de la orden de Predicadores / escrita por 
                  Francisco Ximenez ; paleografia y anotaciones de Carmelo 
                  Saenz de Santa Maria.
       EDITION: 1. ed. del manuscrito original.
     PUB. INFO: Guatemala : Sociedad de Geografia e Historia de Guatemala, 
                1977-
   DESCRIPTION: v. : ill. ; 26 cm.
        SERIES: Biblioteca "Goathemala" - Sociedad de Geografia e Historia 
                de Guatemala ; v. 24-25, 28-29
         NOTES: Vols. 5-7 edited by F. Gall.
                Includes index.
                Bibliography: v. 1, p. lxiii-lxvi.
 
      SUBJECTS: *S1 Dominicans. Provincia de San Vicente Ferrer de Chiapa y
                  Guatemala--History--Sources.
                *S2 Guatemala--Church history--Sources.
                *S3 Chiapas (Mexico)--Church history--Sources.

----------------------------------------------------HU HOLLIS# ADT1913 /bks
        AUTHOR: Comision de Estudios de Historia de la Iglesia en 
                  Latinoamerica.
         TITLE: Bartolome de las Casas (1474-1974) e historia de la iglesia 
                  en America latina : II encuentro latinoamericano de 
                  CEHILA, en Chiapas (1974) / Comision de Estudios de 
                  Historia de la Iglesia en Latinoamerica.
       EDITION: 1. ed.
     PUB. INFO: Barcelona : Editorial Nova Terra, 1976.
   DESCRIPTION: 298 p. ; 21 cm.
        SERIES: Coleccion El Sentido de la historia ; no. 11
         NOTES: Spanish or Portuguese.
                Includes bibliographical references.
          ISBN: 8428005826
 
      SUBJECTS: *S1 Casas, Bartolome de las, 1474-1566.
                *S2 Catholic Church--Latin America--History.
                *S3 Indians, Treatment of--Latin America.

----------------------------------------------------HU HOLLIS# AQU2996 /bks
        AUTHOR: Luque y Ayerdi, Miguel Mariano, bp. of Chiapas.
         TITLE: Primera carta pastoral / que el Illmo. Sr. Dr. D. Miguel 
                  Mariano Luque y Ayerdi, dignisimo Obispo de Chiapas, 
                  dirije a todos sus diocesanos.
     PUB. INFO: Puebla : Imprenta de M. Corona, 1884.
   DESCRIPTION: 16 p. ; 21 cm.
 
      SUBJECTS: *S1 Catholic Church--Pastoral letters and charges.
       AUTHORS: *A1 Luque y Ayerdi, Miguel Mariano, bp. of Chiapas.

----------------------------------------------------HU HOLLIS# AOS8261 /bks
        AUTHOR: Catholic Church.
         TITLE: Officia concessa dioecesi de Chiapas.
     PUB. INFO: [Mechliniae, H. Dessain, 1882.]
   DESCRIPTION: 2 pts. 12mo
 
       AUTHORS: *A1 Catholic Church.
                *A2 Catholic Church. Liturgy. Breviary. Chiapas.

----------------------------------------------------HU HOLLIS# AXE9146 /bks
    AUTHOR: Nunez de la Vega, Francisco, 1632-1706.
     TITLE: Constitvciones dioecesanas del obispado de Chiappa, hechas, y
              ordenadas por su senoria illustriss. el senor maestro d. fr.
              Francisco Nvnez de la Vega, del orden de predicadores, obispo
              de civdad real de Chiappa, y Soconvsco. del consejo de Sv
              Magestad, ano de MDCXCII.
 PUB. INFO: Roma, En la nueua imprenta, y formacion de caracteres de
              Caietano Zenobi, entallador de nuestro senor papa Clemente XI.
              en la gran curia Innocenciana, 1702.
DESCRIPTION: [8], 164, 142, [30] p. 34 cm.
     NOTES: Second part has caption title: Libro segvndo de las
              Constitvciones dioecesanas directivas de este obispado de
              Chiappa. Dispuestas en forma de cartas pastorales, hechas por
              el illustrissimo, y reverendissimo senor m.d.fr. Francisco
              Nvnez de la Vega ...Ano de 1695. (Dated 1696 at end)
 
     NOTES: "Cet ouvrage, fort rare ... est surtout curieux pour les details
              qu'il contient, relatifs a l'ancienne histoire du pays de
              Chiapas. Ces details, ayant en partie le mythe de Votan pour
              objet, se trouvent de la page 8 ... a la page 10 ... Dans la
              2e partie, page 131, se trouve la IXe lettre pastorale,
              traitant des erreurs de la secte idolatre de Nagualisme."-
              Brasseur de Bourbourg, C.E. Bibliotheque mexico-guatemalienne.
              1871.
 
  SUBJECTS: *S1 Catholic Church--Pastoral letters and charges.
            *S2 Chiapas (Mexico)--Church history--Sources.

So by looking through these 12 records we've collected quite a few potentially useful LC Subject Headings.

It's worthwhile to try a SU search for Chiapas --if only to see the RANGE of subjects where Chiapas is the first term:

HU GUIDE: SUBJECT HEADING LIST          283 items retrieved by your search:
FIND SU CHIAPAS
------------------------------------------------------------------------------
   1 CHIAPAS HIGHLANDS MEXICO --ANTIQUITIES
   4 CHIAPAS HIGHLANDS MEXICO --SOCIAL LIFE AND CUSTOMS
   5 CHIAPAS HIGHLANDS MEXICO --STATISTICS
   6 CHIAPAS INDIANS
   7 CHIAPAS MEXICO
  18 CHIAPAS MEXICO --ANECDOTES
  19 CHIAPAS MEXICO --ANTIQUITIES
  87 CHIAPAS MEXICO --ANTIQUITIES --EXHIBITIONS
  88 CHIAPAS MEXICO --ANTIQUITIES --PICTORIAL WORKS
  89 CHIAPAS MEXICO --APPROPRIATIONS AND EXPENDITURES
  90 CHIAPAS MEXICO --ART
  91 CHIAPAS MEXICO --BIBLIOGRAPHY
  92 CHIAPAS MEXICO --BIBLIOGRAPHY --CATALOGS
  94 CHIAPAS MEXICO --BIOGRAPHY
  98 CHIAPAS MEXICO --BOUNDARIES --MEXICO --TABASCO STATE
  99 CHIAPAS MEXICO --BUILDINGS STRUCTURES ETC
 100 CHIAPAS MEXICO --BUILDINGS STRUCTURES ETC
 101 CHIAPAS MEXICO --CENTENNIAL CELEBRATIONS ETC
 102 CHIAPAS MEXICO --CHURCH HISTORY --SOURCES
 104 CHIAPAS MEXICO --CHURCH HISTORY --SOURCES --PERIODICALS
 105 CHIAPAS MEXICO --CIVILIZATION
 107 CHIAPAS MEXICO --CIVILIZATION --CONGRESSES
 110 CHIAPAS MEXICO --CONSTITUTION
 111 CHIAPAS MEXICO --DESCRIPTION AND TRAVEL
 137 CHIAPAS MEXICO --ECONOMIC CONDITIONS
 147 CHIAPAS MEXICO --ECONOMIC CONDITIONS --PERIODICALS
 148 CHIAPAS MEXICO --ECONOMIC POLICY
 151 CHIAPAS MEXICO --EXPLORING EXPEDITIONS
 153 CHIAPAS MEXICO --GEOGRAPHY --CONGRESSES
 154 CHIAPAS MEXICO --GUIDEBOOKS
 155 CHIAPAS MEXICO --HISTORIOGRAPHY
 156 CHIAPAS MEXICO --HISTORY
 157 CHIAPAS MEXICO --HISTORY
 199 CHIAPAS MEXICO --HISTORY --ERRORS INVENTIONS ETC
 200 CHIAPAS MEXICO --HISTORY --FICTION
 202 CHIAPAS MEXICO --HISTORY --PEASANT UPRISING 1994
 205 CHIAPAS MEXICO --HISTORY --SOURCES
 214 CHIAPAS MEXICO --HISTORY --SOURCES --BIBLIOGRAPHY --CATALOGS
 218 CHIAPAS MEXICO --HISTORY --SOURCES --CATALOGS
 219 CHIAPAS MEXICO --HISTORY --SOURCES --PERIODICALS
 221 CHIAPAS MEXICO --HISTORY --16TH CENTURY
 222 CHIAPAS MEXICO --HISTORY --16TH CENTURY --SOURCES
 223 CHIAPAS MEXICO --HISTORY --17TH CENTURY --SOURCES
 224 CHIAPAS MEXICO --HISTORY LOCAL
 225 CHIAPAS MEXICO --INDUSTRIES
 226 CHIAPAS MEXICO --LANGUAGES
 228 CHIAPAS MEXICO --MAPS
 229 CHIAPAS MEXICO --PICTORIAL WORKS
 230 CHIAPAS MEXICO --PICTORIAL WORKS
 231 CHIAPAS MEXICO --POLITICS AND GOVERNMENT
 240 CHIAPAS MEXICO --POLITICS AND GOVERNMENT --PERIODICALS
 241 CHIAPAS MEXICO --POPULATION
 243 CHIAPAS MEXICO --RELIGION
 245 CHIAPAS MEXICO --RELIGIOUS LIFE AND CUSTOMS
 246 CHIAPAS MEXICO --RURAL CONDITIONS
 247 CHIAPAS MEXICO --SOCIAL CONDITIONS
 264 CHIAPAS MEXICO --SOCIAL CONDITIONS --PERIODICALS
 265 CHIAPAS MEXICO --SOCIAL LIFE AND CUSTOMS
 271 CHIAPAS MEXICO --SOCIAL LIFE AND CUSTOMS --CONGRESSES
 272 CHIAPAS MEXICO --SOCIAL POLICY
 274 CHIAPAS MEXICO --STATISTICS --PERIODICALS
 276 CHIAPAS MEXICO ASUNTOS INDIGENAS COORDINACION DE
 277 CHIAPAS MEXICO CONSEJO ESTATAL PARA EL FOMENTO A LA INVESTIGACION Y
     DIFUSION DE LA CULTURA
 278 CHIAPAS MEXICO DIOCESE CATHOLIC CHURCH
 279 CHIAPAS MEXICO FOMENTO A LA INVESTIGACION Y DIFUSION DE LA CULTURA 
     CONSEJO ESTATAL DE
 280 CHIAPAS MEXICO PROCURADURIA GENERAL DE JUSTICIA --HISTORY
 281 CHIAPAS MEXICO SECRETARIA DE GOBIERNO COORDINACION DE ASUNTOS INDIGENAS
 282 CHIAPAS MEXICO STATE --HISTORY
 283 CHIAPAS REGION MEXICO --CHURCH HISTORY
This set of 283 books gives us plenty to chew on.