Bank A- owned by Holding Company
Bank B- owned by the same Holding Company
Title Company B- a wholly owned subsidiarty of Bank B

Bank A refers Title Company B:

Wording on disclosure is:
This is to give notice that Bank A has a business relationship with the settlemnet service provider listed below:
Title Company B, a wholly owned subsidiary of Bank B

Question- should I also reference how banks A&B are related and does the holding company need referenced also?

I would add that "Bank A and Bank B are both subsidiaries of Holding Company"