I get your frustration, but you will be the one coming out looking like a jerk, no matter what. You call them out, you're starting drama. You don't invite them, you're catty. They're users, and, unfortunately, they're part of your family, so I think it's going to be hard to prove your point without alienating some of your family members & creating tension with parties not involved in the disagreement.
If you do invite them to something, make it a point to give them very literal instructions on what you need from them, beforehand & during. My question is, does anyone actually ask them, to their faces, or beforehand, to help out? To tell them what's expected of them? Ie - Sue, you're on drinks, or dishes, or whatever? Or does everyone just take on the helping out themselves & then bad mouth them afterwards? In my experience, even the lazy people will feebly help when they're point blank asked to help.
In the meantime, I would advise you to suck it up & let it go. One lesson I learned a long time ago was not to stress over other people & the things they did, that are not in my control. You can control yourself. Let go of the negativity, it's not worth it, they don't care at all, and you care too much.
Also, by not inviting them, you are really hurting their kids, not them, because they won't learn their lesson, because they don't think they're doing anything wrong. You won't change them, as people, by purposely not including them. Think of how it would be, to be their kids. Poor things.