S1/S2 Mixed Environment Confusion

I have several S1-era pieces that work just fine. Slowly building my S2 next gen ‘family’. I’ve got both   S1/S2 apps working just fine on my iPhone. Want to add S2 app to my iPad (which has the S1 app currently installed and working perfectly).

 In order to add S2 app (to iPad), my understanding is I have to remove the S1 devices and then reset the app → that allows me to add S2 app and S2 devices to iPad → then I go back and re-add S1 era devices.

1) Is all this correct or am I wildly misguided? 2) Will this process completely wreck my happily co-existing iPhone S1/S2 marriage?

Any help/guidance would be most appreciated.