Jose Antonio Robles, Tlaltenango & Gertrudis Rosalia Melope/Merlopes, Ahualulco

I'm having an impossible time trying to find a marriage, baptismal or any other kind of record for this couple and their infant daughter Eugenia Ines. The three came from Guadalajara to Monterey, CA May 1797 as volunteer settlers. According to a California mission record of their child's 1821 birth, Jose Antonio Robles was from "Taltenango en el Obispado de Guadalaxara, Pueblo de" and Gertrudis Rosalia Merlopes was from "Agualulco en el mismo obispado [Guadalaxara], Pueblo de". However, JA Robles' son Secundino told historians in 1877 his father was born in the city of Zacatecas and married at San Francisco. His "relacion" had many inaccuracies though.

I found a few Melope surnames in Ahualulco de Mercado on Familysearch and with such an unusual surname it's probably Gertrudis Rosalia's family but I could not find a baptismal. She was born around 1777. I can't find anything for either JA Robles b.~1775 or the infant Eugenia Ines b.~1796.

I don't know if the records are not indexed or just don't exist. It seems there should be something. I would greatly appreciate any ideas or hints.
Thank you
Pamela Curry