How to trigger purchasing document approval for adding a new line to a PO with different cost center

Summary: We have come across a change order scenario that our purchasing document approval rules aren't routing quite how we would expect. The scenario is: new line added to purchase order with a cost center code that isn't on the original order. We're able to trigger a rule using a condition of the increase to the total amount of the order, but it's routing the approval to the cost center manager for the original cost center code, rather than for the cost center code of the new line.

I'm hoping that by including a condition that specifically triggers for the addition of a new line, this may then route to the correct cost center manager.