I have both an S30 and an S50 and use Android tablets to control them. While it is not currently possible to switch between them inside the app, it can be done externally.
First, connect to your S30 and leave the app running. Next, turn on your S50 and wait for 'ready to connect', then go to the Connections section of your phone or tablet. It will show that you are currently connected to the S30. The S50 should appear in the list of available networks. Choose the S50 and wait for it to connect. Finally, return to the app which will now show connected to the S50.
It's a bit cumbersome, but it does work.
Don