Here is what I have in mind.
1. Pick the texture ((lets say its 256 x 256) you want to add to the main Big Texture
2. Pick the Big Texture (1024 x 1024) and select its quadrant
3. Script to automatically place the 256 texture in the select quadrant of big texture.
4. Automatically scale the UV's of the smaller object to match the new quad....
so end result I have the object with same texture and UV's but they are now using a different texture...
dont know if there is anything like this that already exists.. any help is most welcome.