Not every person with BPD has a fibbing problem of course, but in this case it's an issue. Even when confronted with evidence, my sister-in-law (23) has a tendency to lie if a) it will get attention onto her, b) if she's gonna get in MAD trouble, or c) it'll effect her pride.

Some of these lies are BIG ones, and potentially dangerous if things escalate again (sh*t has gone down). I simply don't know how to respond. With her BPD, I'm not even sure she knows when she's lying.

Help please.