I think it depends on the crestie--I have one that seems to like it when I mist--she closes her eyes and starts licking at the water right away, and I have others that run away as fast as they can!
She'll probably be just as happy to have a nice big tank all to herself anyway! If you ever do house more two together, the new one always needs to go through a 30 day (minimum) quarentine period, and there shouldn't be a large difference is size between the two (females only!)