Don't let a side quest for understanding get in the way of doing - or demanding - care and kindness.
To avoid the trap of trying to satisfy a group member who can never be satisfied, think about what you owe everybody else.
"Oh, we just tell people my partner is dying for funsies, that way we can hear all about yoga, religion, and diets in excruciating detail, I love getting medical advice from non-doctors!"
If someone averages 36 hours between responses, what happens if you assume that their response time will be 36 hours?
It's okay if someone you strongly dislike gets an inkling that the feeling is mutual.
Like the creative writing workshop advice goes, if one person tells you a piece of feedback about your story, that's just their opinion, but if ten people give you the same note, there's probably something worth paying attention to on the input side.
Your house, your rules, so spell them out from now on and give your son-in-law a chance to surprise you.
Soft rejections, mixing finances, and a primer for dealing with loaded questions.
Here is blanket permission to not worry very much about offending people who neither show up to your parties nor ever explain why.
"Don't touch me" isn't complicated. You know who makes it complicated? CREEPS, THAT'S WHO.