I have a tiny "unofficial" appartment on the mezanine in my 600 ft shop, which is in an industrial area about 6 miles from where I live, and I absolutely love spending time there. In fact my dream is to have an 1100' shop with a 900' appartment and 200' deck over in, perhaps, a nicer area.
But thats just for me, your situation may be quite different when you take your daughter into account. For instance, some of the things I would need to consider are;
How old is she?
Is she likely to live with you for more than the next couple of years?
Does she have an interest in garage things?
How does she feel about living in, and having her friends over to, an appartment over a shop, as opposed to a nice little house with a lawn and plants and things, right outside the door?