Costing Of Configurable Material

We have a scenario here.

We create the sales order in the sales Plant

We do a STO to Production Plant where explode the BOM which has an configurable sub-assembly

When we run an MRP this creates a another STO for the configurable material to be produced in the supplying plant.

Now, the questions are

1) How do I create the cost estimate for the configurable material

2) How do I get it to reflect in my parent order.

Thanks

Siva