Like many of you, I had the adoption glitch, where the child (Lucia from Whiterun) would say "I need to get my things" but not actually move to my house (Windstad Manor, all 3 additions added, but not fully furnished). Then, she DID move to my house, but would still say "I need to get my things" and then walk back to Whiterun. On top of that, my wife (Aela) would just stand still in my kitchen holding a torch, acting like she doesn't yet live in the house. So both my wife and child were glitched. I was angry.
Someone in another thread suggested that maybe the child needs a chest to "store their treasures." I already had the beds, of course, so I then built every container and chest possible for the bedroom areas. I then fast traveled to Solitude. While in Solitude, I fast traveled to Solitude again (not sure if this did anything, but that's what I did). Then I fast traveled back to Windstad Manor. While still outside, I fast traveled to Windstad Manor AGAIN (once again, I don't know if this did anything, but this is exactly what I did). I then entered my home, and voi la - both Aela and Lucia were un-glitched! Lucia thanked me for adopting her and Aela started [censored]ing about the bears and wolves outside.
I haven't adopted a second child, and since my steward seems to have claimed the second child's bed, I don't think I'll try it for fear of more bugs. One child is enough anyway.
The moral of the story is: build all the bedroom containers. Hope this helps someone else.