A letter writer to The Moneyist wrote that

…political issues came up, and our daughter-in-law wanted to discuss and debate them with me. I calmly reminded them of our previous agreement [that there would be no political discussions among them].
Since January, our son and his wife have stopped communicating with my wife and me. They have refused to return our phone calls or respond to our texts. We have been told that our daughter-in-law does not wish to have contact with our family.

The letter writer added that we have also tried to respect the boundaries they have established.

First, it’s not just the daughter-in-law who has broken off contact. So has the son, who plainly has gone along with his wife, perhaps actively sides with her for the same reasons she has for refusing contact. It’s not inappropriate for a husband to support his wife over his parents, so there’s nothing to be read into that aspect. Both son and daughter-in-law are affirmatively not wanting further contact with the parent; that’s the boundary they’ve set.

Against that, the letter writer wonders if he and his wife should cut the two out of their will(s). A potential complication is that the letter writer has another son, only mentioned for his existence, so I assume (yes, yes) that this son is on good terms with the letter writer.

My position is this, because I tend to be a bit black and white on such things. The son and daughter-in-law have taken themselves out of the letter writer’s family. The only tie, such as it is, remaining is the accident of birth involving the son. Their removal of themselves—as the letter writer notes, they were not driven out—also took them out of any familial-related connections and obligations.

The parents would be well-served to acknowledge their son’s decision, not impose themselves on him—honor the boundaries they have established—and rewrite their wills (each parent should have his/her own will), and allocate their estate elsewhere. That’ll be hard to do, emotionally, but it’s necessary according to the son’s and his wife’s boundaries. That reallocation might also lead to friction between the son and daughter-in-law and the other son, but that’s among those three; it’s irrelevant to the fact of the two having decided to leave the family altogether.