Not all the Arandas Church records have been extracted or indexed, although most have been. There is one film of baptisms in the period you are interested in that is not. Marriage records only go back to 1802, but the matrimonial investigations go back into the 1790s, although none are indexed. Looking at the dispensations from the Diocese of Guadalajara may reveal something on the family; it is a long shot, but still worth the effort. There are a couple of websites that have indexed the films, and there is also book, Sagrada Mitra de Guadalajara, that is worth a look.