I'm looking for a solution to add Setup Costs to a Manufacturing Order. The case is we have a machine, which has to be setup at the moment we are going to produce a different size end product. 

This Setup is done by a third-party company, and is invoiced on a an hourly-rate. Setup time is between 3 and 5 hours, and the costs for this service has to be distributed over the produced items. So the setup costs have to weight heavier on a small batch, as on a large production. 

Costs are charged after setting up (as the setup time is kind of variable), but before finishing the end product.   

As Service is provided by a 3-rd party, I want to purchase the costs, at receival I would like to alter the purchase to the actual hours.

At the end I want to see these service charges in the valuation of the produced items. 

Could somebody advice how I can achieve this?