I am trying to arrange multiple pieces of an outfit to fit onto the same texture. Some of these outfit pieces are already unwrapped before being imported to Blender, and so cannot be re-unwrapped as they have no seams. Some pieces have mesh caches on them, so they cannot be joined into other objects without destroying their vertex indices, and thus breaking their caches. Other objects are being unwrapped for the first time in Blender.
In order to properly arrange and optimize my UV islands, I need to be able to view all of these object's UV maps at the same time. I could export all their UV maps as images, arrange them in photoshop, then re-import that and align their UV maps to the image, but this is imprecise and inefficient.
My googling has turned up that the usual method is to join objects together, but I can't do that. Is there any other way I can work on multiple object's UV maps in blender at the same time?