Not ISEmpty ( FIlterValues ( List ( RELATED_TABLE::PASSWORD2 ) ; PASSWORD ) )
will return True (the number 1) only if Password is one of the values in the list.
The other option would be to go ahead and add a new relationship that uses Password and Password2 as match fields in the relaitionship.
This was what I was looking for! I've never used FilterValues before. Thanks for the quick response, Phil.