EDIT: I got it to work. Thanks for the help! Just had to wait for a bit longer after adopting Sofie, and I got her to move in to my homestead.

Going to get this locked.

That happened to me once.

Try marrying an NPC before adopting.

I did, married Perth.

ask him to move home and see if the kids move home too.

Also it is best to adopt 1 kid then see them at home and get the forced thank you dialogue when you enter the home. after that go and adopt the other kid.

Perth is already at my home with Alesan, and the Thank You dialogue has occurred. I'll try again but I don't know.

I don't know what else to suggest.

I think my file may be corrupted some how. Thanks for trying to help, though. I could always delete it and start over. Haha.

Closed by request of OP