To OldOlds - Do you have something that you are passionate about? Something that is very important to your life? It could be a sports team, or craft beer, or Lord of the Rings, you get the picture. I recommend that you set up a ZOOM call on this subject with a number of your friends who share this passion, and invite (insist, in the name of family cohesion) that your FIL attend. If this thing were something that your FIL was not exactly on board with all the better. On the call, you and your friends can extol the virtues of said thing, and discuss in detail the minutia and internal disputes. But most of all, you must INSIST that love of this subject is the only way to live, how can anyone NOT find this appealing?
Sounds absurd, doesn’t it? (Or you could share this commentary with your FIL).