Reference dimensions in virtual component?

Hi,

I know how to reference dimensions in other parts in equations, which can be done by like =d1@sketch1@part1.sldprt.

However

1. if in one assembly you have two virtual part A and B, both are saved internally within the .SLDASM file, then in A how do you reference a dimension in B?

2. if there is an external part C saved as an individual .SLDPRT, can it reference a dimension in A or B (both within its enclosing .SLDASM)?

Qi

SolidworksAssemblies