In the very earliest years of Natchitoches, a Spanish fort, Los Adais, was the nearest settlement. There were conflicts between the two communities but there was a priest and a church and the records for the Spanish fort/church are reportedly in Mexico. It is likely that some of the settlers had functions that occurred at Los Adais. Conversations with the library at the university were unsuccessful though they did report that they knew of "some" records in Mexico but had not tried to obtain copies.
The BOSSIER, CHAIGNEAU/CHANEAU, BUARD and other lines are all from the very earliest years and some of the records about their lives and deaths are missing ... perhaps in the Los Adais records?