How to Add 2 different PTO Accruals as one and end date the 2 Accruals?

Dear Gurus,

My Client using Accrual Plan A, Accrual Plan B, both the plans accrue 1.25 leaves to each employee in the organization irrespective of the employee position/grade for every month, now the requirement is they want to add A&B and create new Accrual Plan C(2.5 leaves every month), and balance of both elements to route to C and end date Plan A&B with immediate effect, as we are in the mid of the Absence year, how achieve this, please suggest.

Another requirement here is, once employee takes 15 days in a year for Plan C, HR should know about that as a notification/alert, how this is possible in simple way, as i want to avoid much customization in it.