Hello Mr Gonzalez,
You and I are cousins because Maria Eufrosina Lafon is my ancestor's sister. If you send me a backchannel with your contact information I can give you more information. I also own the only known photos of some of the Lafon family. I would be happy to exchange information with my Mexican cousins (my grandmother, still living, is also a Gonzalez).
Anyway, to answer your question. You are referring to the children of Dr. Antonio Fernando Lafon baptized at Real de Catorce. My ancestor was one of them. The reason she is called 'Maria de refugio Chapa' is because she was by this time a widow for a 2nd time and she used several different names after that. But the earlier 2 baptisms back in Matamoros (and I believe, before Maria de Los Angeles was remarried) the parents of Antonio Lafon are indeed given as Ramon Lafon and Angeles Garcia. That is also what she is called in Dr Lafon's own death record in 1890. Only in the baptism records of Real de Catorce is she referred to as 'Chapa'.
I also have some other information about Emilio Manuotou if you are interested.