To the question of the mole’s identity, UD takes a Shakespearean approach: Cherchez the bastard child.
True, Tiffany’s no bastard; but she’s close to it. She’s the much-overlooked fruit of his brief, disastrous, marriage-killing adultery with Marla. Kind of an embarrassment.
That is, he married Marla for sure, but it was dumb and he got out quick, but then there was Tiffany, who is no true Trump, and is treated that way. She not only lacks the sylphlike splendor of the legitimate line; much more tellingly, she actually seems to have earned her educational credentials.
Tiffany knows the law; she studied it at Georgetown. She knows just how evil Dad’s actions are. This and this alone might be able to destroy the patriarch of the family against which she has long harbored burning resentment.