Hi Haley,
I would say the best way to do this would be to use the workflow. I would use the template to populate a field like Suggested Group, then create a descision (Yes/No) in the workflow to check to see if that field is populated (SuggestedGroup is not NULL). If it's populated (not NULL), have the workflow auto assign the ticket to that group within your workflow. If it's not populated, let it run its regular course. The assignment on the main window gets populated automatically based on the current assignment value that is found in the database.