Does this method work??
I've been trying to get adoptions to work and the closest I've got is the children say "I just need to gather my stuff... I'll meet you there..." And they never show or move from the place I last talked to them.
Also, how do you attach a basement to the main house so that the kids go into it?
I'm still learning of course, but I'm thinking maybe your house isn't navmeshed properly...or maybe not at all. NPCs can't follow you otherwise. Just a thought.