How to handle institution acquisitions (Schwab/TD Ameritrade)

Schwab just acquired TD Ameritrade. All of my accounts were automatically transferred from TDA to Schwab.

 

I added Schwab to Mint which creates the problem of each account appearing twice. Deleting TD Ameritrade would alter my historic data.


What is the best way to manage this transition within Mint so my TD Ameritrade accounts no longer appear as duplicates to my Schwab accounts without losing my historic data from previous years?