I think the proper way of modelling this kind of relationship is to have two entries in the Relationships table. Otherwise, the semantics of the fields change depending on which way you are looking at the relationship.
So rather than having mem,ber and member2, you would have relationship_owner and related_person, where your model class should take care of creating both relationship entries in a add_relationship method or similar. This will also make your queries a lot easier. For example, for a father/son relationship, you will have:
relationship_owner related_person relationship
Daddy Bob Little Joe Son
Little Joe Daddy Bob Father
When you are querying for everybody who is a son, you only need to look for a “Son” relationship, rather than having endless conditions on (member=some_id and relationship=‘Son’) OR (member_2=some_id and relationship=‘Father’)