Wow, what a bad situation with your family members. They don't sound like the kind of people one would prefer for neighbors even if they weren't family members.
I agree that your taking the "high road" and trying to see how your chickens are getting loose would be the best all around. If anything it would show your own good character~~which is definitely something your "neighbors" seem to be greatly lacking in, unfortunately.
i know theres nothing I can do if the dog gets one but I felt like he was threatening me. This dog is in the house or tied, he would let her loose on purpose. I have netting over the top and Im going to fix it up, it was just his attitude.
That is a nasty way to voice things! I'm even more sorry it was from family even!!!
If you keep your chickens up, just remind them that you'll take no responsiblity for what may happen to their dog if it gets one on your property. Maybe they'll get the point they over stepped.
Like it was said before... someone may be letting them out. I have to put a lock on my coop. Just at night... but you can't always trust people.