Ok, here it comes with the pictures. The goal : mirror subassembly so that components create respective constraints inside mirrored assembly, and depend one on another - not on their originals placement.
1. Start point. We will mirror RIGHT_HANDED.ASM about TOP_ASSEMBLY datum plane. PLUG.PRT is constrained to COVER.PRT and our goal is that PLUG_MIR.PRT is similarly constrained to COVER_MIR.PRT.
2. This and the next slide constitute "independent placement" for PLUG_MIR.PRT which means it will try to re create constraints. Pre requisite for this : all placement references of plug.prt should reside inside RIGHT_HANDED.ASM (and not use higher level assemblies references). here it works - PLUG.PRT has references to COVER.PRT only.
4. Here is a result : PLUG_MIR.PRT has 4 constraints. All to COVER_MIR.PRT.
it will not move if PLUG.PRT moves, but only if COVER_MIR.PRT moves.
5. This is how PLUG_MIR.PRT redefinition looks - hope like what you desire.
6. IF it was mirrored as "Dependent Placement" (Dependent means "dependent on source component position only") :
it will not move if COVER_MIR.PRT moves, but rather if PLUG.PRT moves.
7. Last note here: "Dependent Geometry" is about Mirror Merge dependency state - will it update by source model geometry change or not. Can go either combination with "Dependent Placement" option, they have no inter dependency.
Very nice! One question; how did you get to the mirror subassembly dialog in the scond step? I cannot seem to get to that dialog.