Hi Depeesh,
Yes, you have to run a dummy model to get an overall C.G. However, it is not necessary that, for a multibody part, you have to use shared topology. You can create a multibody part without shared topology as well. You can quickly create a multibody part for those parts only for which you want to check C.G. without using shared topology.
The other option is to use selection information, select the bodies for which you need information, and then use selection information to get the desired values.
You are navigating away from the AIS Discovery experience