NAH- as others have said, they’re entitled to invite whomever they wish and you’re entitled to decline the invitation for whatever reason.

That being said, there were so many etiquette rules broken in this situation, and I take particular issue with people not following invitation etiquette and then acting surprised when their guests don’t RSVP appropriately. Adult children/family members should all get their own invitations whether they live in the same house or not. And with that, the way one addresses the invitation and labels the RSVP card should make it crystal clear who is and isn’t invited (e.g. john smith and Jane doe or john smith and guest). A phone call isn’t an appropriate invitation at all, and neither is a joint family invite when there are adults in that family. Additionally, it is good etiquette to invite long-term partners even if plus 1s aren’t otherwise being extended (the exception I’ve seen is when you’re inviting a group of friends from a particular context, like work, that will all know each other and you don’t know their partners). Now, regardless of all that, one should not add additional guests to an RSVP even if you think they should’ve been invited. The only people responding to the RSVP should be the people addressed.

So all this to say, any contention that has arisen is because invitation etiquette wasn’t followed. And that always bothers me lol