How to prevent the charge account from being recalculated when a requisition line is returned

Summary:

When a requisition line in the manage requisition line tab is returned to the requester, the charge account is recalculated according to the rules in place. Is there any way to make a rule to keep the charge account that the requisition previously had?

Content (required):

Here is the use case:

1. Requester A creates Requisition A with charge account AA-AA-AA according to account rules, which he changes manually to AA-BB-BB. The charge account is saved.
2. Requester A submits the requisition, which ends up in Buyer B's Manage Requisition Line workspace. (still has charge account AA-BB-BB)
3. Buyer B returns the requisition line to Requester A