OTOH, suppose it's a home, and that a child can be shown to be suffering harm from her parents' smoking -- are you going to claim that the parents' property rights are more important than the child's health?You're assuming that I'm accepting the second-hand smoke myth.
The "for the children" argument is such screamingly, laughably politically-correct received wisdom, I'm embarrassed for you for even presenting it.
You didn't answer the question. Suppose, for the sake of argument, that a child
can be shown to be suffering harm from her parents' smoking. Are you going to claim that the parents' property rights are more important than the child's health?
That would be a case where property rights are in tension with the rights of other people to not be harmed. Children are good subjects for the example due to their inability to voluntarily leave the premises.