Sounds like a couple of kids need a good ol' fashion spankin'. Find someone who has the nastiest, meanest, mini around and let them have that. Maybe when the mini kicked the crap out of them a time or two they would have a little more respect around animals and settle down with the loud mouths too. Someone needs to kick their little buts. They obviously have no respect and no hearing since they do exactly what they are told not to so someone needs to put them in their place. Would not fly around my place. My kids push the limit some, but ask them if they would go to someones house and act like that. Thankfully my kids spend time at the neighbors house mostly, with their little friend over there and I have a great neighbor who will not put up with their crud if they get out of line either. She has not hesitated to wash their mouths out with soap when needed. Worst case scenario, they get sent home to deal with me or their dad. They know a lot about moving rocks, scooping poop, sitting in a corner...you name it and I am sure they are well qualified in it. Just have your cousin send her kids to my house for a month. After they rotated through the neighborhood doing work for everyone and being eyeball deep in minis for awhile they may change their mind and their attitude.