I, too, don't want CAS to be so limited in terms of relationships. In fact, here are some possible options:

-A teen and younger can be created without an adult or young adult but with an elder as a grandparent.
-A teen and younger can have a legal guardian and not a blood-related parent.
-A teen and younger can have an older sibling as their legal guardian.
-A teen and younger can have an older relative as their legal guardian.
-A teen can be created without older Sims and be considered an orphaned teen and can either have younger siblings live with them for the teen to take care of them or just for the teen to be alone, but as long as teens can be created alone without any parent or legal guardian (great for stories or for those who just want teens without older Sims to be stuck with).
-Roommates to have separate last names.
-The ability to choose the relation (uncle, aunt, cousin, etc.).
-The ability to choose a relationship type (friend, best friend, roommate, boyfriend, fiancé, spouse, friends with benefits, f*** buddies, enemy, etc.).


Any other ideas that I missed?