Internal Order Settlement - Default receiver for a Cost element

Dears

I am in a stand-still at the Internal Order Settlement.

A cost element group is used in the AllocStructure for external services.

Out of the cost elements posted, one cost element (Training Fees) should always be settled to a Cost Centre (100%).

Other Cost Elements should only be settled to Asset (100%).

I created the settlement rule with amount specification. But the settlement leaves a residual amount 0.01 still to be settled.

(We have separate currencies and hence exchange rates).

Even this amount specification confuses the user as every period they need to see which one is not yet settled and which are settled.

What is the best option in this case ?

I cannot change the cost element group in source structure.