Hi chunkybeah!

Glad to have you joining us!
And congratulations both to you birthday and your upcoming wedding!
I can tell there seems to be a lot of stress going on in you about the situation with your sister in regards to your wedding. And I am sorry you are feeling that way, already now almost a year? ahead of time.
I wish there would be something I could say or do to take some of that stress of your shoulders. But there really is not much you can do to be able to control what your sister will choose to do or not... . But there is still a lot you can do for yourself to relief some if not all of the stress that is consuming you right now!
Learning a bit more about the disorder and also learning more about how to best communicate with a family member having BPD might also greatly improve the prospect of a successful outcome on your wedding day. .
Here is an article that might be of help to get you started:
Staff Article - Before You Can Make Things Better, You have To Stop Making Things WorseOne of the most important things to understand in improving a relationship with a pw BPD is that you may not be able to make them change - however in changing some of the ways you deal with it and work on your communication with them, can change things a lot to the better. which you can see if you read up a bit on what other members here have accomplished in their relationships with either significant others or family members suffering from this disorder.
I think you will find a lot of inspiration and hope in engaging and posting on the staying board here for people who want to improve their relationships with their BPD's in their lives. You will find that board here:
Staying: Improving a Relationship with a Borderline PartnerI think it is important to understand that there usually is no malicious intent behind the actions of a pw BPD, instead they mostly react in accordance with feelings of fear, and fear of pain and abandonment in particular.
Also, you have time. The wedding is not tomorrow, so if you could try and perhaps give the worrying part of this issue a bit of rest and instead try to focus on the joyful parts of your wedding plans and take some time to learn from our boards and the lessons and information about improving a r/s with your sister, it will help you relief some of all that stress that right now is creating a lot of worry in you.
Also let us know how we best can support you at this time?
What is it that you worry most is going to happen on your wedding?
What would need to change for you to be able to feel more at ease or less worried about your sisters presence at your upcoming wedding?
Remember, we are here for you and we want to help!
Best Wishes
Scout99