(Nick Galifianakis/for The Washington Post)
Advice columnist

Dear Carolyn: I am getting married this July. My fiance and I at some point told my younger sister she would get a plus-one. She said she was going to bring her best friend from college, and I cautioned her at the time that she might want to wait in case she gets a serious boyfriend between then and the wedding.

Now my sister is in a serious relationship, and my parents are pressuring my fiance and me to allow her to bring both the boyfriend and her best friend, saying I might regret not inviting him if my sister and her boyfriend get married.

My parents and fiance already have a somewhat rocky relationship and this is threatening to make it worse. Am I wrong for standing firm and saying she needs to still bring just one?

— C.

C.: Probably, but not for the reason you might think.

A guest with a plus-one-plus-one is silly.

But, the idea that a sister qualifies as merely a guest is silly, too.

And the idea that you’d either disinvite the best friend or exclude the serious boyfriend just because you don’t, what, want one extra plate? is silly. Especially since your parents could cover the cost, given how invested they are.

Of course, for the best friend not to just say, “Hey, bring Boyfriend in my place, I totally understand” also is silly. Unless there are airfares involved, I suppose.

That I’m now four contingencies into an analysis of one extra guest to a wedding is making the college degree I earned to qualify for this job feel silly.

The thing about silly expectations and silly concessions and silly rule-following, though, is that it’s all so easy to fix. You add a guest, someone bows out, someone chips in extra — meaning, you figure it out and Drama stays in its dressing room oblivious to all the fuss.

Yet you’ve presented this as Drama. As something that isn’t silly and that you can’t just figure out — and that’s my problem with your “standing firm.” It should never have mushroomed into a standing-firm standoff kind of event.

So, why did it?

This: “My parents and fiance already have a somewhat rocky relationship and this is threatening to make it worse.”

Assuming my between-line reading skills are sufficiently sharp, your fiance is digging in, in part if not entirely based on resentment of your parents. Or sister. Or both. And your parents are pushing back hard.

Yes, no, close enough?

If so, then you need to stop treating this as a “My knucklehead sister invited her bestie!” problem and see it for what it is: a power struggle between your family of origin and family of choice. One that’s taken a turn for the petty.

A bigger problem still is that you’re not calling it what is: You’re neither agreeing with your fiance and telling your parents to back off — not with conviction — nor agreeing with your parents and telling your fiance to back off. Instead you’re peacekeeping — backing your fiance because it’s harder not to and asking me if that’s right.

It’s not, because “right” is about peace of mind: Consult your values and gut, do what those say, then take the heat for it.

Easier said than done, but easier done than dodged.

Write to Carolyn Hax at tellme@washpost.com. Get her column delivered to your inbox each morning at wapo.st/haxpost.