This is all very close and I totally agree with #1. There in lies the problem.
Having the Charter in possesion makes no difference as I don't have any of mine, their all in a desk in the respective homes.
The Steward sleeps in one of the small beds on the second floor. (Un-Owned) as they can double as your follower. No followers have "owned" beds in your home.
As I said earlier, your home does need to be "kid ready" but you can do them one at a time or both at the same time.
One bed = one adoption
Two beds = two adoptions
The only thing I did not try is building two homes with two bedrooms. That would mean we could in theory have 4 kids.
I did not take the Whiterun option to expand.
Yeah, I'm being very careful. I made Lakeview my 'family house'. Kitchen, bedrooms and a trophy room... seems homy enough and I can't see having a whole wing for a storage room unless there is something special about it, since there are tons of chests in my house now. How could I possibly need more storage? There's very, very little I need to add to the place to finish it completely and even that stuff is for the upstairs b/r's and cellar. Looks like it won't be long until I'm on the prowl for a wife, then kids.
Maybe it's a good thing, but I got the glitch with Breezehome. I originally bought the alchemy lab intending to make it a b/r. I wouldn't have gotten it otherwise, since I'm not much into the alchemy stuff. After buying it (and, of course, not receiving it thanks to the glitch) I found out about the glitch, so I just left it well enough alone. No alchemy lab should mean no chance of the kid accidentally moving there. Keeping fingers crossed, but I'm thinking it might be a glitch that actually worked out in my favor... in which case, I might have to blow a gasket if I think about it. lol