I have been supervising a therapist who works at a local agency. He has expressed concern that the secretary at the agency has been accepting and reciprocating social invitations with active clients. The secretary is also romantically involved with the owner of the agency, a therapist of the same sex. One client involved was a 19 yo with some orientation confusion who was invited by the secretary to a party which was basically for gay/lesbian singles and/or couples. Another incident involved an active client and her mother who invited both the secretary and the agency owner to dinner.
Other than presenting his concerns to his supervisor (the agency owner) are there other steps he could or is obligated to do? I do see this as a serious ethical violation and wondered if or when a problem may arise from this would it reflect on my supervisee?