My answer posted in the Guru section:
Each escrow account is a separate account under RESPA and you must follow the guidance in 1024.17 which has no provision for you to treat multiple escrows as one for the annual analysis or the treatment of shortages or surpluses.
You cannot apply one account's surplus to another's shortage without the express consent of the borrower
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The opinions expressed are mine and they are not to be taken as legal advice.