Hello Kittykat681
How wonderful you are getting married, congratulations !
I can relate to the feeling that everything is feeling overshadowed by the threat of your BPD mum possibly going to ruin things for you.
Have you heard about FOG ? (Fear - Obligation - Guilt)
https://bpdfamily.com/content/emotional-blackmail-fear-obligation-and-guilt-fogUs children of BPD tend to feel more fear, obligation and guilt towards our BPD parent than average children would, simply because we were groomed to do so from a very young age.
You are actually allowed to choose the wedding you want. You are free (even if you don't feel that way) and you can even decide to not invite your mum.
I like NN also remember from other people's posts that sometimes the suggestion was made to have some friend who's aware of your mum's issues, look out for you during the wedding. This friend could redirect your mum if things would be turning awkward.
You could indeed open a new thread, clearly stating in the subject that you have a question about getting married. Or you could hit the 'search' button and search through 'wedding', 'getting married', etc. I just tried and it gives quite some results.
Please let us know if you find the info you need.
xx