Select a part that is already open in SolidWorks without showing it

I would like to get a modeldoc2 that is already open in SolidWorks without the part becoming visible. I am attaching to the part now by using ActivateDoc(PartName) but the parts become visible as each one becomes active. It seems like I have used a command that gets the modeldoc2 without the part becoming active but I cannot find what it is.

Can someone help?

Thanks.

Dan Miel

SW 2014 SP03.

SolidworksApi macros