How to Retrieve working part & Other part in Model Compare Feature using NXOPEN ??

I am Working on NX 10 Model Compare Feature using NXOPEN (UF_MODL_model_compare). I want to Retrieve working part and Other Part 2 in Model Compare feature.

I can retrieve Working part (Part1) by
Dim workPart As Part = theSession.Parts.Work &

I want to know how can retrieve other parts (Part 2) by using NXSession

Dim secondPart As Part =theSession.Parts.?????????