Well I would be very surprised if Monica would be Dizzy, do I think she has told everything what happened between her, mom and Dad in the past, I doubt that as well and who knows maybe there is also a connection with his mother that could lead to right of MC to part of the money or a link between his his Mother and Dizzy. (In my countries laws the MC would have had at least a right to a 50% share in the Moms inheritance, even if the dad would have had a right of use as long as he lived and the dad would not be able to thwart the MC's right to that part by a will).
On the other hand we know Elaine is also working on ways to contest the will or get MC at least a part of it if he fails his part, at least if we believe she has indeed good intentions.