Thanks for reply again. You don’t need to do more. I have solved the problem in much the way you describe. I installed third party launcher Nova as well as Tasker.
In short, when the controller is Bluetooth connected, dmd2 must be opened when Nova is opened. That way I get directly to dmd2 when I use the controller and leave Locus or other app. Otherwise the phone works as usual. Thankyou again fore a great product.