I would probably not take my dog unless I'm paying an extended visit. Like I said, my shih tzu refuses to 'get over it' .. not saying your MIL's won't, just relating what I've experienced. My GSD is pretty full of himself so those types of displays aren't bothersome - I'M the one that can't stand the noise!
Unless your MIL is willing to leash and correct her dogs for their behavior, it may not get better.
Xan Varik von Fernheim (born 4/3/13)