Size-mismatched PC and vest—what to do?

[BobF]

The situation: several months back I bought a kilt outfit on Facebook Marketplace. I haven’t had a chance to wear the Prince Charlie jacket and vest yet, but with Burns Night approaching I’ve been preparing. Unfortunately, long story short, the jacket (marked Raymond of Doune, by Lochcarron) is a size 46 and the vest (not separately marked for maker) is size 52. Even pinning up slack at the vest shoulders, it hangs way below the edge of the jacket. Not sure how the seller wore it this way. Anyway, it’s clear that I won’t be wearing this vest for Burns Night, and it seems way too large to take in without completely remaking it.

1. What are the chances of being able to swap vests with someone and have the fabric match?

2. Are PC jackets always worn with a vest? Can I get away without the vest, or should I just wear a different suit jacket to the event?

3. Any other advice?

Thanks!

Edit: I’ve just learned that the vest/waistcoat I received is actually an Argyll vest (five buttons) and so clearly was not part of the outfit to begin with.