Final answer:
A Marriage and Family Therapist is the most relevant professional who can address the concerns between the husband and the daughter from a previous marriage and work towards improving the relationships within the blended family.
Step-by-step explanation:
The MOST relevant professional to whom a referral should be made is a Marriage and Family Therapist. A Marriage and Family Therapist is specifically trained to address the dynamics and issues within family relationships, including stepfamily dynamics. They can help address the concerns between the husband and the daughter from a previous marriage and work towards improving the relationships within the blended family. They can also provide guidance and support for the entire family during this challenging time.