Accounting Flex Field - Repointing to Another One

We have one instance with 2 general ledgers.  Both have the same accounting flex fields except for one.  (Meaning the Cost Center, Company, Global account used the same accounting flex fields.)  However, there is one flex field that they do not share - it is the Local Account.  They are named differently, but are the same length.

 

We would like to move them to the same flex field, ensuring all of the values used by both general ledgers are in that common local flex field.  And yes, the screen allow you to do this - point to another accounting flex field.