This is probably a stupid question. I've made a small baby quilt and have already done minimal quilting and put the binding on. Could a longarmer stipple it after it's been put together? My DD wanted more quilting in it and I just can't do it.

Yes, possible and doable

It works, I quilted a quilt for someone whose Mother had hand quilted both ends, and the middle was empty of stitches, her mom passed away, and she wanted it quilted.
I was amazed, it worked.
Best Wishes!
Sue

Shouldn't be any problem...