Fortunately most of these folks don't (or most likely can't) make this garbage up themselves, so just block the originators one at a time. Eventually all you'll get from your aunt are kid pictures, cookie recipes, and other aunt stuff.
You also have the option of citing sites like Snopes when the BS gets too deep.
Here's something I posted when that "Jade Helm" nonsense was going on:
“Here the big battles were being fought-against revised versions of the Bible, fluoridation, dirty books on school library shelves. The people of Garden Grove cared enough about the future of their country to pass an ordinance prohibiting the sale of UNICEF Christmas cards. At PTA and school board meetings in a dozen communities, women had the courage to stand up and reveal how Democrats were building barbed-wire stockades in Alaska to imprison all conservatives.” The Last Days of the Late Great State of California-Curt Gentry-1968
“plus ça change, plus c'est la même chose”- Jean-Baptiste Alphonse Karr
I wish Facebook would feature an "enemies list". Then it could suggest friends from the enemies of your enemies.