I don't know what made me look at this particular post, but please explain to the OP, in detail, why she has any obligation to let her ex know her address once their child is a legal adult and no longer subject to court orders.No. It's not a "moot point". OP said nothing of hiding the child. The OP has already been advised by a Family Law Attorney from his/her home state.
Based on your statement are you attempting to assert that the OP is legally mandated to let her ex know her address for the rest of her life, even once their child is a legal adult? If a family law attorney in her home state said that she is required to do so even though her child is about to turn 18, then I will suggest to the OP that they wait until the day of their child's 18th birthday to schedule the moving truck....because I am certain that no family law attorney would state that she was required to provide her address to her ex once the child was no longer subject to court orders.