We are working on a project whose LEED Boundary covers the whole exterior area of the site, but there is an existing building that will not be altered. We have the rainwater collection area on the roof of that building, that we are considering being outside the project boundary, like a "donut hole".

Can we consider this roof area being a rainwater collection area and a rainwater management strategy in SSc4 Rainwater Management? 
The rainwater collected from this roof (outside the LEEDBoundary) will be used as a nonpotable water source for the certified building (WEc2 Indoor water use reduction). In this case, the runoff surface would be outside the boundary, but the retention surface would be inside the boundary, considering that all those areas are within the same site.