You have to be a little careful though. My brother (also a lefty) taught me how to play pool lefty and now shooting right feels weird but I have no control on the left side. It is kind of funny, actually, but probably not helpful to you.
As far as knitting left, if you don't want her to knit on the right then you could probably teach her by knitting backwards. I think there is a video on this site, or I found pictures here (http://www.drgirlfriend.com/knittingbackwards.html