Who can I confide in about my cousin's BPD tendancies?

[CuzICare]

I am reconnecting with a cousin whose behaviors strongly resemble most of the nine common characteristics of someone with BPD.  I am reading up on the condition and conferring with my wife to help understand what we are dealing with, as this beloved person is increasingly dependent on us for support.  Cuz recently relocated nearby from a distant state, and most of what we know of her past is from what she confides in us.

We are now getting texts and emails from past neighbors and distant relatives who want to know how Cuz is doing after the move, as Cuz is not responding to their correspondence.  Cuz also doesn't want us talking to other people about her.  We feel it necessary to reply to these inquiries, but don't know if these others are aware of her BPD tendencies.

So I guess I would like opinions in two areas:
(1) How can, or should, we explain why our beloved Cuz does not respond to their correspondence without revealing our private concerns; and
(2) For the relatives that know something is different about Cuz and seemed concerned, is it a bad idea to start having a dialogue with those family members about symptoms associated with BPD, or is that something we should not bring up since it may reveal mental health information that was not in their thoughts?

[Turkish]

You're being triangulated by your Cuz, though BPD or anything else aside, I think it's valid to respect her wishes. If she doesn't want to share, that's her business.  Her relationships with whomever exist apart from yours. I can imagine it's tough being caught in the middle, even unintentionally.

Aside from your relationship with her, I would give a BIFF response. Brief, Informative, Friendly, Firm

Step back from rescuing her or others. You aren't responsible for the relationships between her and others. 

[Jareth89]

I confided in nobody really about my family's situation...yet. Families do need support if a member (son/daughter) is involved with a pwBPD but it depends on how reliable the extended family is, whether they are likely to have your family's back or whether they would treat this kind of news as 'gossip'. I don't necessarily think a pwBPD has a right to privacy if they are abusing a family member or a whole family. The pwBPD often engages in activities which damage the privacy/reputation of others. In your case however, unless you need support, there seems no reason to discuss it with anyone.