COMPUTED AND ASSIGNED MASS PROPS TO RELATIONS

I have an assembly model that I need to place coordinate systems at the CofG position for both the computed and assigned results, is there a way of doing this via parameters? Each model in the assembly has an assigned CoG position and mass. At the assembly level I can get the assigned values using MP_CG_X etc but can't figure out how to get the computed values - any ideas please?

Cheers!