DSis is getting married soon, and one of her bridemsaids is a childhood friend who grew up on the same street as us. Recently said friend mentioned that her brother had been '"really upset" at not being invited to the wedding. Friend's brother is a few years younger and DSis was friendly with him when we were all young, but they're hardly what you'd call friends now. The wedding is also in a different part of the country to where friend's brother lives, as DSis moved away a few years ago. So DSis was a bit taken aback that he'd been expecting an invite, but felt guilt-tripped into saying he could come. This weekend she found out that he's bringing his GF too (who DSis doesn't even know).
DSis is upset as there are friends of her and her fiance who are only coming to the evening reception as they were trying to keep the ceremony small, so if they were squeezing in extra people it would be their actual friends, not random relatives of the wedding party and their partners. Add to that he's now turning round and being a bit arsey about 'not being invited originally but being invited now' 
I know DSis should have just said no to begin with, or at the very least said there wasn't room for the GF, but she's a quiet, polite girl and doesn't want to upset anyone. I'm quiet and polite too but I feel like phoning up DSis' friend or her brother and asking them who they think they are guilt-tripping her into inviting them and causing her stress before the wedding. And telling him if he's going to be a dick about it then he should just not come, as was the original plan.
Sorry, this is long and very boring, but it's winding me up and I needed a rant.