Is it inappropriate to invite these people to a bachelorette party if they aren't invited to the actual wedding?
ETA: My god, getting married brings up a lot of invite/do not invite etiquette questions. This came up after I posted earlier today. I've been engaged for less than a month and my mom wants to throw a family engagement party for us on the Saturday after Thanksgiving. She wants to invite both of my fiance's parents. However, they're literally in the middle of a very unfriendly divorce. The engagement party isn't going to be a lot of people or at a large place so it's not like the two of them could reasonably avoid each other.
Whether or not his mom brings her new girlfriend (a very sore subject with her ex-husband) it would be extremely awkward to have both of them there. My fiance's opinion is basically "whatever" because he's tired of his parents acting like children about each other, but I really don't think it would be a good idea to have them both there.
Should we invite his mother because we'll have spent Thanksgiving with his father just a couple days beforehand? Or should we invite his father because my fiance has a SLIGHTLY better relationship with him? Neither? Both, because they're grown-ups and should be able to handle this shit?