Multi-Site using Multi Resource Scheduling - Have Questions

Looking to touch base with anyone that uses multi-site and the mutli resource scheduling board. Looking to see if resources (people) can be flexed between sites. Currently, when we setup a new employee, we associate them to an applicable Resource Group in the primary site they will be working in. A resource can only be associated to one Resource Group at a time. We also have a Master Scheduler who schedule project phase jobs for all our Engineering teams. We just acquired another company (site 3 now) and want to be able to use resources from Site 1 to flex to Site 3 without having to keep switching the Resource Group that resource is in. Happy to setup a virtual meeting to discuss more details if anyone has ideas or contacts to help brainstorm solutions.

Also interested in this subject. i would be willing to meet if needed.