Crusader Kings III

Crusader Kings III

LotR: Realms in Exile
Getting Rid of Wilderness Holdings
Hey there! I kind of misunderstood at first of how to gain wilderness holdings (now I know that you can colonize them) so I got some via a war with Tom Bombadil. But now I can't convert or colonize them. How do I get to interact with them again in a proper way? If I give them to a vassal they also stay wilderness.