"What do I do with Delia all this time? "

Both of my kids have done their time sitting quietly with a book (or a Gameboy) outside the other's classes. You can say that during Monday hell, everybody (both Delia and Fiona) are responsible for entertaining themselves during other people's commitments; that's their contribution to the household. Your contribution is getting there; their contribution is behaving well during the part of the evening that isn't focused on them.