While researching my own family genealogy I came across a database that I had not come across before. It contained great information and not to mention I got many new clues as to where to search for documents.
If it was helpful to me, I think it can also be of help to you. The name of this database is called Solo Genealogia and it is being run and maintained by Jesus A Chacon.
It is mentioned in the main page in Spanish that:
This compilation is based on information taken from parish registers and genealogical works including references. We welcome any comments, suggestions or modifications necessary in order to show the correct information. We greatly appreciate all those who have contributed to this database.
To test it out just enter de la Garza to get an idea of what information you can find in this database. It may be a long shot but enter your ancestors names to see if they come up.
Screen shot of Genealogical Database of Solo Genealogia:
Let me know in the comment area bellow of what you think about this database and or if you found it to be useful for your research.