I'm confused. How is LW involved in this situation?

Alice likes low-cut tops. Her in-laws, Bob and Carol, don't like this. They told Dave, Alice's husband. Dave told Alice. Now Alice and Bob and Carol and Dave are all upset. And now Bob and Carol's sibling/sibling-in-law Evelyn is writing a letter to Society Qs because...?

This family seems to have a boundary problem.