I have a breeder friend that lets her yorkies go at 6 weeks also. I, on the other hand, keep my babies until at least 10 - 12 weeks and have kept some even longer. I always send my puppies home with a tube of nutrical and encourage them to give a little a couple times a day. I do know that her babies much larger than mine so that could have something to do with it. Is there some reason that she won't keep it a little longer just so you would feel more comfortable. I had a person request me keep a baby for 5 months because they were going to be out of the country. I did, but it was hard because I grew so attached to little Dottie (you can see her on my webpage) that it was very hard to part with her. Thank goodness they communicate with me all the time. If you can get her to wait a few weeks, you'd be better off.
www.simplyyorkies.com