As I said, you would need to use the auto-assign functionality, which can set group values based on location, but you'd also have to disable DP for the default group as the DP would override any choices made by auto-assign.
The only other thought I would have about this is if there is a scenario in play where you are relying on DP's default group assignment to always work and is why you may not be able to disable DP. Is there any such condition where this is happening?