One thing I will give my mother in law a lot of credit for is that she has always included Bil in family social events. For example, there is an expectation that if she is invited to a wedding, that Bil is invited too. Of course, some of that may be due to the fact that he lives with her.
The question you may ask is: does Bil enjoy doing that?
In a way, I think he does. I've been with him at a couple of these, or crowded dinners. It amazes me he would want to come to a wedding reception. Nowadays, you'd think everyone at a wedding reception has a hearing loss, because the music is always cranked up to unendurable levels. Has anyone else noticed that?
And, people with autism are well noted for their sensitivity to this type of stimuli. Heck, I don't like it either and I'm neurotypical.
But Bil sits there. And I suspect he observes everything, and records it in his own type of way.
When we come down next, the end of April, my mother in law and Bil will be away at a wedding when we arrive, so what we find out afterwards will be interesting.