Stick with the original defense:
If there is no response after a first and a second admonition, a judicial committee should be formed.
So if they decide to go to a JC now, they aren't following directions. You stated you aren't going to cause problems. Let them know how offended you are by their insistence on breaking up your family. Hint at legal defenses.
If they still try the JC I would personally threaten legal action individually against each member, and demand testimony from each and every witness who says they saw the post on FB.