Sure - go into the activity button customization page and next to the volume button you should see a selection in the device column for the Insignia that sends the volume up command. You can choose commands from other devices in the same row and they'll all be sent when you hit the volume button. Just pick a command that does nothing from another device or add another copy of your Insignia as a passthrough and use that to select an additional inoperative command.

Or just buy a real receiver and DVD player.