Thankfully my in laws love our puppies. They come over every sunday for their "play date" with their grand dogs!!!! I love it cuz the kids are so worn our when grammie and grampie leave they just flop right down and go to bed. Tonya, I know the feeling when someone acts annoyed with your babies and it does really hurt your feelings, but just remember that they love you more than life itself and the MIL will get hers. Not everyone can be an animal lover as all of us here are, but they still need to respect the fact that we are and always will be and if they don't like that, the I say "tuff doggie doo" to them.
Good luck. Let us know how the dreadful visit goes.