They eventually move out, tho. that's always the thing. Mansions aren't usually designed to downsize well.

Our family has a two-apartment house with a shared garden, and we leave the interior-apartment doors in the stairwell unlocked. That way you can huddle down in one apartment and expand into the second when there's more people, or rent it out.

Like this.

https://baumentor.de/wp-content/uploads/2019/09/mehrparteienhaus-hanse-haus-1024x512.jpg