Yes, you can create new groups from material zones, IF those material zones already exist on the model, and if you're using Poser 10 or higher. I'm not sure if it works in Poser 9 or below. (The group editor tool got a major overhaul in Poser 10).

Open the group editor, create a new group and name it whatever you need, then click the Add button and you'll get a dropdown menu. Select Material from that menu and you'll get another dropdown menu listing all the materials that currently exist on the model. Select whichever material you want to be in that group. The selected area will turn red on the model, showing that it is now part of that selected group. Rinse and repeat until you've created all the groups you need.