1. It would't confirm it, Donald is an asshole who might as well screw people over from his grave.if it was Monica it would mean that Elaine's accusation of having hit on Donald would be confirmed, Monica would have completely betrayed the trust of MC's mother and then that of MC himself (there is the suspicion that the third heir knows the conditions of everyone's will)
2. She wouldn't, for her to keep it a secret is only fair, because it allows the MC to make his own choice so he doesn't feel pressured to pick whatever