How to split a household in the Sims 1 Legacy?

Elden Hick has decided he wants to become a rock star and move into his own place. But I can't for the life of me figure out how to move Elden out of the house he shares with Mama. 

I don't see an option on the phone, computer or newspaper. The neighbourhood view only offers the option to move both out (evict). There doesn't seem to be a way of splitting a pair in the Family bin either (I tried with the Roomies). 

Googling hasn't popped up anything useful although one suggestion was to have another Sim ask him to move in with them - but even if that worked he'd be stuck with a roomie he doesn't want (and a second Sim in the house to play which is what I'm trying to avoid).

When I first played this house years ago when Superstar came out I did the same - Elden moved out and became a Superstar. Mama kept her Culinary job, trained all the dogs to the max and went on to win many trophies at the Dog Shows.

How was I able to do this back then? Was it a mod? Does their relationship have to be so negative that she asks him to move out (not even sure if that would work)?
I just don't remember how I did it. 

Any/all suggestions welcome and thanks for reading. :)