Well, you get what you pay for.
Do a search for "N tracKs Studio"
It is definitly not at the level of professional software. It will mix, with a various degree of quality. I think they offer a time limited demo that functions. I was at a studio once that was waiting on their big rig and they were using the N track program. It is a resource hog though..better have a decent machine.
Disclaimer. I would use it for emergency purposes only and..I have never used it. I just remember it.
Anyone know of something better for this application?