Q. My 14-year-old son saved his money and bought an e-bike at his mother’s home. The stipulation was that he always wears a helmet when riding it. Two of my friends called me recently and told me that my son has been spotted riding around the neighborhood without a helmet. They sent me pictures. His mother isn’t doing anything about it. What’s good ex-etiquette?

A. My first question would be how do you know his mother knows? Did your friends also call her? It sounds as if you are anticipating she knows, and you are angry because she’s being lax about enforcing the helmet agreement. I suspect that’s not the case.

If you are truly co-parenting, this is what should have happened. (I realize hindsight is 20/20. I’m listing this for others who face these kinds of decisions.)

First, did you a

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