Financial Project Plan Resource Quantities Overridden by Project Plan

We use the Project Plan for high-level resource planning and synch resources and dates to the Financial Project Plan using Update Financial Project Plan and Progress from Project Plan.

If we subsequently adjust a resource's planned quantity/hours directly in the Financial Project Plan, these changes are overwritten the next time the process is run, based on the quantity held in the Project Plan.

We have reviewed KB166830, but it does not resolve this issue.

Is there a way to retain the planned quantity/hours maintained in the Financial Project Plan while continuing to synchronise resources and dates from the Project Plan?