I've seen this work where it wasn't optional, ie, that's where parents with small children and babies were expected to sit. My favorite is thenopposite: mid-morning movie showings for parents, usually moms, where they can bring their babies with them, and baby noise is expected.
As a university student, the nearby theatre had a young mothers' room at the back. It had windows to watch the screening and piped in sound. The mothers could settle down infants without disruption. My childhood church had a similar room.
I wonder if this could work for fine arts?
If I remember correctly, there was a room at the back of Orchestra level at New York State Theatre that was sound-proofed, with sound piped in. I'm sure I heard at least one interview where someone in NYCB said they brought their child, so that the child wouldn't disturb anyone.