My wife has her passport (still valid for 3 more years) and NEXUS card with her maiden last name. So she can travel using it, just buying the tickets with her maiden name.
However, legally she assumed my last name after geting married (driver license, health card, etc).

As per NEXUS rules is she supposed to update her passport and Nexus card with her new married name? Could it be a problem not doing it?

We just had a baby and we're going to apply for the baby's passport and Nexus. So in case it's really needed, she may apply for them as well.

Thanks