Trump’s wife was a legal United States citizen when the kids she had with him were born... were they not?
His first wife was not a citizen when Trump's first three children were born.
His third wife gave birth to his fifth child in March of the same year she became naturalized, but I've never read just when in that year she became a citizen.
The only child of Trump's who we know is an NBC (according to the birth era) is the illegitimate one he had with his mistress at the time.