How do I adopt children when I'm using the hearthfire DLC?

Solution 1:

You may only adopt up to two children in an un-modded Skyrim game. You say you have already adopted two children, so you won't be able to adopt any more even if the ones you have are living at different properties as you're at the adoption cap.

There is a Multiple Adoptions mod available that raises the limit to 6, but it recommends starting a whole new game due to the way already-running scripts are written into the save data.

Solution 2:

You can adopt up to 2 children, unless modded. There are 5 places where you can adopt children. You will also need to completely furnish you homestead if you want the family there. Otherwise, if you live in a city house, buy a kids room.

1. Dawnstar Quickysilve Mines: Alesan

2. Solitude Katla's Farm: Blaise

3. Whiterun Gildergreen: Lucia

4. Windhelm Dock Gate: Sophie

5. Riften Orphanage [Must complete Innocence lost, which starts with Aventus Arentino in Windhelm]: Runa Fair Shield, Samuel, Francois Bueatfort, Hroar.

If you want to adopt more than one children, get the Multiple Adotion Mod so you can adopt more than 2 children in the game.

For unadoption, get the Unadopt Children mod which adds a power to reset childrens' al.