Quite simple. First, for safety's sake, clone the group and hide the backup. Next you need to assign all the objects in the group a dummy texture (be sure it's the SAME texture). Ungroup it, pick one of the objects, and collapse it to an editable mesh (right click, quad panel 1 >convert to

. Go into the editable mesh parameters in the modify panel and scroll down to where it says "attach." Click that button and select all the other objects you want to merge. Deselect attach and open up the material editor. Change your dummy texture's type to "multi/sub-object" and set the number of textures to however many different textures were present in your origional group. Recreate those textures in the texture slots for the multi/sub texture (note that each box in the main interface of this texture type allows you to create a standalone texture which can be named independently to help you keep track. Just be careful that you don't drag-copy existing textures into one of these to try and save the trouble of recreating it- you'll lose the whole thing). Once you recreate all your needed textures, tab back to the modify panel and apply a MeshSelect modifier. Go into polygon subobject mode and select all faces that would have a single texture, and while keeping subobject mode on apply a Material modifier. Change the "material channel" until the texture you want on those faces shows up. Then you apply another MeshSelect, grab the next set, and apply a new Material modifier. Repeat this process until you've got all the faces textured. You can check the material channel for a particular texture by looking in the material editor for your multi/sub texture and seeing which channel number corresponds to the texture itself. All you have to do now is fix the pivot point for your new mesh object and you're good to go! I recommend making the origional group undrenderable (edit>object properties>uncheck the "renderable" box) and freezing it (display>freeze selected, check hide frozen objects box) just in case something goes wrong so you'll have a backup. Hope this helps.