The issue here appears to be the wanting to use quite a few figures in a scene. Much more than about 12 to 15 figures, and you can forget it. Poser was never designed to handle multiple figures at once. Also, conforming the clothing to the figure will work -- your issue is going to be crosstalk. Creating a new figure bu combining the existing meshes won't save you much on system memory. haven't downloaded the file (doing so is something of a TOS violation), but based on what I'm seeing here, and your only recent familiarity with the program, you may not realize this is all :)

thou and I, my friend, can, in the most flunkey world, make, each of us, one non-flunkey, one hero, if we like: that will be two heroes to begin with. (Carlyle)