Multiple SEPMs using same license

We have setup multiple SEPMs between our global and internal networks. We did it this way for many reasons, but the main one was to keep the environments separate. For example, we have one SEPM for internal users, one SEPM for hosted users in STL, one SEPM for hosted users in Europe, and another SEPM for hosted users in Virginia.

With that said, we are looking to "sync" our licenses for reporting reasons. It seems that using the same license key for each SEPM gives us the full seats back and we don't want to be in jeopardy of misusing our licenses.

Is there any way to have all the SEPMs "talk" to each other so we have an accurate seat count?