Matthew went and talked to his mom and she said that it was fine with her as long Dynisha came home once a week. So it looks like we've added a member to our household. We'll fix her up a room over the next few days. We have plenty of spare bedrooms. Jamie has two himself, but we're going to give her the guest room, which is larger. Tonight she is sleeping in Jamie's room like she usually does when she spends the night. While the kids are at school I will fix up the guest room for her as best I can. Right now it's full of Christmas stuff we haven't hauled back up to the attic yet. The hard thing is that the room doesn't have a closet. We wanted it for a workout room and guest room combo so we put a murphy bed in the closet. For now I've cleared out space in our hall closet for her clothes. If this truly turns out to be a permanent situation we'll definitely redo the room.
Dynisha is really happy. I can tell she's also worried we won't really let her stay. She pulled me aside and asked if I thought we'd get along when she moved in. I told her that we wouldn't always. They'll be times when she's mad at us and times we're mad at her, but that we love her and that won't change and we won't make her leave. I explained about how things would be different with her visiting versus her living here (rules, chores, homework, etc.). We are also all aware that her mother can change her mind at any point.