I think I should have posted this on the sibling board. Sorry! Learning the ropes here.
That is an interesting idea; I'd also be curious what the take would be on the Coping & Healing Board to such a thing... .
But, the idea of my ever talking to my Husband's siblings regarding his BPD traits (their Mom has full-blown BPD and is textbook High Functioning BPD) actually never entered my mind as the topic of the day (so to speak). I've spoken with my Sister-In-Law about her dealings with my Husband's oldest brother, and she doesn't see these traits in him. I've spoken with my 2 other Ss-I-L (my Husband's younger sisters) about their
own BPD traits, and then as a side topic, my Husband's behaviors that are similar. All of these conversations, though, have come about in relation to their Mom and the torture she puts everyone through on a regular basis
Now,
as the topic of the day, I've spoken with my 4 younger sisters about my Husband's symptoms and behaviors, and we've all commiserated on subjects where we share the problems. We've listened to each other where the other Husband is worse with certain things, and congratulated where things are better. For one of us, or all of us
We are a close-knit family (I'm the oldest of 6; just one brother), and we females have
always been open and honest and sharing of our lives and experiences--good and bad. Only one sister knows that my Husband's--and hers--behaviors could be considered a mental illness, and that's because her Husband is way worse and I've given her the "Stop Walking on Eggshells" book that helped me so much, so we are on the same page in knowledge of the disorder.
I guess it all depends on the relationship you have with your Husband's siblings. And if what you say will be held in confidence if you have fears of him finding out about such a conversation and if he'd feel violated or betrayed in some way. I know that the stuff I've shared with my Ss-I-L and sisters will never be shared, so I'm free to be honest with all of them and pick their brains when I need advice, as they pick mine when they need it. Not sure any of this helps you out, but maybe the Coping & Healing Board will glean better fruit for you