It is not possible and not supported at this time.
You cannot have a single VCAIM monitoring multiple vCenter configurations.
You would need 1 agent per vcenter.
Additionally it would not be recommended to run a SpectroServer with Sysedge host with VCAIM on it as it results in a model that represents the same system (the SS) as the VNM model and causes various problems.
A VCAIM can monitor itself as a Virtual Machine (VM) but if that VM is also the Spectroserver, you end up with three models of the same system:
The VCAIM/agent host model
The VM model for itself
Which will cause it to not run correctly.
It is important to make sure there is no overlap with one AIM managing another AIM on VM.