How to define resource rate for a new resource and publish it to the BOM without impacting other ite

Summary

How to define resource rate for a new resource and publish it to the BOM without impacting other items

Content

I need to create two resource rates for R&D labor and I need to make them effective in our costing module as well as add them to the appropriate work definitions. My concern is that I need to create a new scenario in order to roll these new rates into production but I am unsure how to isolate these two items and not rollup other skus or raw materials. 

Version

Oracle Fusion Release 13