Product costing - applying planned price for make parts

Dear SAP gurus,

I do costing using ZPC1 variant.

I updated all purchased parts (F) with a new planned price:

1. For all externally purchased parts, instances where special procurement key is blank (MARC - SOBSL field), the new standard was taken from the planned price I uploaded.
2. For all internally purchased parts, instances where special procurement key is NOT blank (MARC - SOBSL field), the new standard was pulled in from the product owner plant where the procurement key was pointing to.

For the analysis I am doing, for the internally purchased parts, I would like the system to use the "planned price" & not take the cost from the product owner. Is there a way to change a setting that would help me doing it but blanking out special procurement keys on the plant level.

Thanks a lot for the help!

Dmitry