Poser contains it's own runtime folder where, in the past, most, if not all, content, would reside.  However, as more content was loaded into that runtime, the program grew sluggish.  IIRC, Poser 6 introduced linking to external runtimes, individually named folders containing runtime folders easily connected to the Poser Library.  Now you can separate content among several runtimes under different categories which can be conveniently linked and unlinked and organized.  

With the current Poser iterations, you still have the flexibility of linking as many runtimes to the main Library as possible.  I number over 25 runtimes on my system, others have many more.  Among those runtimes exist 1 dedicated to Genesis, 1 dedicated to Genesis 2 and another just for the DS core files which I call My Library and is also linked to DAZStudio 4.7.  When I load anything related to Genesis/Genesis2, I load the DS core files into My Library and the Poser Companion files into their corresponding runtimes.  Nowadays, I use the DAZ Install Manager (DIM) to decompress the original files to their appropriate locations.  But word of caution, if you decide to decompress the zips manually, make certain to extract them from the content folders within.  This is something DIM does automatically.  Also, in Poser's General Preferences, set your searches for deep.