Is there a way to boost autonomous household changes for unplayed households ?

Hallo all ,

I am observing my long ongoing save file and despite having neighbourhood stories enabled , there are little changes to the households . 

the way I play , once I choose an heir for my legacy , their siblings are moved to unplayed households . They have kids and die , and that’s when it ends .

the kids of the siblings stay on the lot , if they have children they are adopted , they do not get partners and move out .  Those  linages do not last for more than 2 generations , as adopted kids also stay on the same lots and they are inactive .

one of the task of my heir is to keep family bonds and anytime they have conversation about expanding the family it ends with adoption of a pet or the sim said they are not ready for it .
I would love to see them move out and have their own lives , and populate my world  further . Is there a way to boost that ?