A little update for you all ...
Flynn and Charlie are friends now- even best friends. They have been playing together so nicely and they are back in the one cage, and Flynn feels like the big cage is his home now. Strangely enough my once bossy little boy has totally mellowed and is quite happy to let Charlie take the reigns.
Flynns old cage is still available, and Charlie wanders in occasionally to eat the food, play with the toys and generally let us know she owns thar cage, too.
At night they are sleeping in seperate cages- Miss Charlie needs her space at night!