Non bpd question. does dbt help?

Hi,
I have a sister with bpd recently diagnosed after many yrs.
She has alochol problems as well, and is currently in an unsafe state.
She is attending dbt, and I am wondering what your experiences are with it. Does it help? I believe it can be a long process.
Due to her alchol problems and unsafe state at present, she may be able to go to a residential unit dealing mainly with that, but also continue with dbt and other help.
The unit can be up to 28 weeks, and then supported living.
It's all going to depend on funding and when it may be available.
Has anyone any experience, and did it help at all?
Also is there a genetic link with bpd, as many of my family have struggled most of their lives with very similar problems.
Many thanks
Beana