This came up in conversation with a group of friends, and I haven't been able to find a consistent answer anywhere!
A friend of mine was given a plus one to a wedding where she would not know any of the other guests aside from the bride and groom. She is not dating, and would like to bring her brother as her wedding "date". However, she wasn't sure whether it was frowned upon etiquette-wise to bring a sibling as your plus one.
I couldn't see why it would be a problem, but others weren't so sure. I thought I'd bring it to you fine, etiquette experts. Would it be a faux-pas for her to bring her brother to this wedding?
Re: Sibling as a Plus One?
What I've picked up most from these boards is that etiquette is about treating your guests equally and etiquette rules are not rules for the sake of it, they are designed with the intent of not hurting/offending another person. Thus, having a cash bar is rude to your guests because you are asking them to foot part of the bill for your party, where as a guest bringing their sibling as their date does not affect anyone in any way what-so-ever, therefore, not rude, always acceptable.
If your boyfriend was invited by name you shouldn't have subbed your mom (invites aren't transferable).
And if he wasn't invited by name and just an "and guest" then the hosts were rude.
OK, so we know SOs should always be invited by name. We know invites are non-transferable. We also know it is rude for guests to invite someone/ add someone to the RSVP of their own choosing.
But if the B&G are going to give all of their truly single guests a plus one (and of course they may choose not to, in which case this questions is moot), in which case guest can bring their mom. In the case of a guest invited with SO who cannot attend, is there ever an appropriate situation where guest asks "can I bring my mom instead of my bf?".
Well, it's a given that if you don't at least ask the couple and just assume you can sub someone, that that's rude.
If you ask... I still think it's shady. Because essentially it really is your asking the couple if you can bring an uninvited guest to their wedding. It also can put the hosts on the spot because they might feel like jerks for saying no so they'll likely say yes even if they don't want to. But I might still do it myself if I weren't going to know anyone else at the wedding or if I had to travel for it.
A time where I think it would be to ask is if a couple RSVPs yes and then close to the wedding one can't go anymore. If the guest tells the couple "Hey, SO can't go anymore. I can still attend myself. I have a friend who is willing to come with me if your headcounts are finalized, but I can happily attend by myself. Which would you prefer?" Maybe still a bit on-the-spotty but could potentially doing couple a favor as paying for meals that go to waste is a bummer.
From a host's perspective...
This did happen to me at my wedding. I said sure because I didn't want to be a jerk. But this guest lived in town and had lots of other people at the wedding that she knew / was friends with. So the petty part of me was annoyed at paying $100 to feed some girl I'd never met (and never saw again) even though my friend would probably still have had a good time solo.
This is why I would never ask for a sub unless the alternative to my bringing one would be declining the invite (I'm not a social butterfly so I wouldn't attend a wedding where I knew no one).
The point is that in the grand scheme of things, this really shouldn't be something to get upset over.
The rule of etiquette is that regardless of whether or not the host cares, invitations are not transferable-whether or not they are for non-attending SOs.
Substituting guests can make major changes to the budget, the dynamics, and other arrangements, sometimes at the last minute, and that's why etiquette prohibits it to begin with. If hosts are okay with that it's one thing, but guests should not take it for granted that it's reasonable for them to just do it. That's where the lines of etiquette and "okayness" get crossed.
I'm a host who didn't care who the plus one was, nor if someone brought a substitute.
My SIL brought her BF (best friend). BIL (her sister) brought SIL's other good friend. I seriously didn't care. Another married guest brought a friend because her spouse couldn't make the wedding.
Hosts don't have to care about those things, but if they do, their wishes should be respected, and no substitutions made.