Bridesmaid not participating in after ceremony

My daughter is getting married in May. Her only bridesmaid will be 16, her mother contacted me this morning an informed me, not my daughter, that her daughter will not be participating nor attending the reception or any other bridal activities besides the actually ceremony.
My daughter does not get along with the bridesmaids mother very well, they basically are just cordial to each other. But the girls have been friends for years, even with a 5 year age gap.
Should I tell my daughter and possibly spark a issue, or expect the mother to tell her herself? I have a gut feeling the mother is being this way because she is very strict an people have started rumors that there will be “lap” dancing an such because it is a country wedding with some sassy line dancing involved. Nothing that is inappropriate as I am a pastor myself. I can assure no one will be dancing on anyone’s lap as the rumors say. The rumor starters are just taking song titles and making their own assumptions. For example, Country Girl Shake for Me by Luke Bryan, it may sound like it will be inappropriate but, my daughter is a dance teacher an knows how to keep things modest, especially in the church.