Welcome Andrea2, you are definitely not alone in your Thanksgiving reflections. It's good to see you've already noticed the lessons available here! Lots to learn and lots to process as well!
I couldn't really tell from what you shared, who is the BPD? brother or SIL?
While I understand these behaviors are not about me, they deeply impact me.
Very good of you to know that the behaviors are not about you! If you know they are not about you, do you think you can find a way to process them that will lessen the negative impact on you?
Keep sharing!