Hi sweetums;
Like you mentioned, if you don't feel connected to or understood by a T, it likely won't be a helpful relationship for you. So, of course, you can "interview" therapists first -- ask if they will do a "fit" meeting -- and just see if you feel heard, understood, and like you can relate to the T. I know I've had one initial appointment with a T where I knew at the end she was not the one for me (talked about herself more than I was OK with).
The other part of your question might be professional/technical education. My current T isn't DBT trained or BPD specific, but with her background (LMFT, somatic work, family systems) she has enough to go on to help me navigate issues with my H's kids' mom (uBPD) and stepdad (uNPD). So while professional education/specialization isn't necessarily a requirement, you could certainly narrow your search by focusing on T's who specialize in BPD, or who are DBT trained.
In fact, you could see if there is a DBT center in your area, call them up, explain your situation (it's not you, it's your D with BPD, but you need a T with BPD experience), and see if they could refer you somewhere.
Honestly, DBT can help many people, not just those with BPD -- in the
Family Connections class I'm taking, we work on DBT skills ourselves -- so a DBT center might be a great place for anyone to get therapy!
The
psychologytoday.com "therapist finder" feature (for many countries, not just the USA) may also be a good resource. You should be able to filter by location, specialization (BPD), areas of expertise (DBT), etc.
Hope some of that is helpful;
kells76
