Promoting a bridesmaid to maid of honor

This sounds incredibly passive aggressive toward your MOH and as a guest, this would make me super uncomfortable.

A bridesmaid's or maid-of-honor's total responsibilities are to buy the dress; show up sober in the dress; and smile for pictures.

If you go ahead with your promotion plan, you will embarrass your guests, embarrass your promoted MOH, and end your relationship with the present MOH. You will also make yourself look really bad.

I agree with PPs. I think an alternative would be to give a speech/toast just thanking all of your bridesmaids (and even groomsmen) for being there and for all of their help along the way.

View Quoted Comment Agreed. Also, the use of the word “HORRIBLE” to describe someone’s inability to meet some pre-determined list of expectations that may not accurately reflect what they can feasibly do for you is kind of...yikes. Like, I’ve been in and heard of bridal parties where the MOH/bridesmaid actively tried to undermine the wedding, were rude to the bride and family members, dropped out last minute, etc. This doesn’t sound like someone being “horrible,” imo. And if I were at a wedding where the bride promoted a bridesmaid in front of everyone, I would be mortified and add it to my collection of “horrible things I’ve seen at weddings” stories.

View Quoted Comment

Even doing it at the bachelorette party is awkward for everyone.

Ewww no! This sounds more like a plan to punish and embarrass your current MOH instead of thanking your BM. Do not "promote" her, and do not make a grand spectacle of it at your reception or your bachelorette. If you want to show your appreciation to your BM then you take her out for dinner and write her a nice thank you note.

The only people responsible for planning your wedding are you, your FS and anyone that you hire. Anything else is just icing on the cake. The whole honoring part of a MOH is you honoring your close relationship and dear friendship with the person and the Maid part is quite literally a young woman not someone is who is expected to help or clean up after you.