Sourcing of Raw Materials - Materials Reuse in a Historic Building

I cam here to ask a similar question! I am working on a rennovation of an office building that is exploring BD+C New Construction certification. I am struggling to figure out the Sourcing of Raw Materials credit: The "Building Life Cycle Impact Reduction" credit clearly states "However, reuse materials contributing toward this credit may not contribute toward MR credit- Sourcing of Raw Materials." I am assuming we would need to carefully allocate any reused materials between the credits to not double count. 

I am also hoping to clarify in the case of a renovation to an existing building, what is the baseline for the total project cost. The language is "cost of the total value of permanently installed building products in the project " and does not stipulated newly installed building products - would we need to estimate the value of any of the existing materials in the building as well? 

I have a similar historic project using Option 1 historic building reuse for the Building Life-Cycle Impact Reduction credit.  Were either of you successful in taking credit for "reuse" of the existing building elements in the Sourcing of Raw Materials credit? And what was your strategy for costing these building elements?