We have a LEED v4 ID+C for Retail project that has two water-source heat pumps (WSHP). One of these WSHPs has an OA CFM below 1000, so it is not required to have a monitoring device. However, the other has an OA CFM above 1000 and thus must have one. Our mechanical engineer requested that the monitoring device be installed so that it collectively measures the OA for both units. Would this be acceptable? If so, how should this be explained to reviewers?