Hi. I have a 12-month-old welsh corgi, and I want to know how to discourage nipping. She can be very mouthy while playing, and her nip can sometimes be a bit painful, although they never break the skin. I have a 2-year-old son, who doesn't seem to mind this, but I still don't like it when she does it to him. I also have another baby on the way. What do I do to teach her that it is unacceptable?