I went to adopt Frodnar and Dorthe, but at my house only Dorthe was there, and I can no longer adopt any other child (Frodnar is still at the orphanage) It says both child beds are owned, no matter what house I move too, I've tried my own in The Pale, and Breezehome in Whiterun, they both have child bedrooms, with child chests for both kids, why can't I adopt my second child? I can no longer talk to stray children, or the people at the orphanage, and I cant go back to a previous save, because realizing I had to wait a few days for my children to end up at my house, I went off and did a lot of quests, I did 3 Daedric quests finishing the Oblivion walker achievement, and a ton of over misc. quests. (Im on Xbox)
Ok. In Breezehome, there are 2 beds. Your master bed, and a followers bed.
In most other houses, the same thing applies so make sure you have 2 non-owned beds not including the master bed for your children.
Second, if you own the DLC houses, you may want to build a bedroom addon as well as the main halls 3 beds. Because you can obtain a Bard, a Housecarl and a Steward, thats 3 beds taken already. It's basically all based off of free beds.
And 2 children is the limit as-well.
Also, you said you have 2 beds taken up and only one child. Its because your housecarl owns one and Dorthe most likely owns the other.