for me this sounds like different tenants which would be a truesight usecase to use different reals im RSSO. but for this you would need a seperate TSIM for each of the tenant. then the data would be completely seperated and maintained in the seperate TSIM's, accessible over 1 TSPS.
on the other hand an option could be use patrol events only and tag them somehow in the respective cell since you are pushing the events to different cells. if you use the server thresholds in TSIM then all the data is going into the same TSIM DB, so it will be very hard to get information where the data came from.
there is some similar request Can we have TSIS details in events? but if none of the above helps raise a support issue with BMC, i have not found any way of webservice or commandline to get such informatoin