Q: How to index the names when the mother's and grandparent's last names are recorded as given middle names?
A: See Basic Indexing Guidelines: Names, Given Name or Surname.
Some records contain names that are not easily identified as given names or surnames. This can be especially difficult if you are not familiar with the naming conventions of the culture the individual was from.
If you cannot determine which part of the name is the given name and which part is the surname, or if there is only a single name listed, do not separate the names into the Given Name and Surname fields.
Keep each name in the same order as it was written on the record, and type the information in the Given Name field.