I have a bunch of M4 Decos that I'm going to switch out for XE75 Decos.

What's the best way to make that transition?

I presume I'd add the first one via the app and then convert it into being the primary (not sure how but guessing something in the app would do it).

But the primary needs to be plugged straight into my modem and so I'm not sure how the app or network will handle things if I unplug the primary and replace it with a new Deco that isn't yet marked as being the new primary.

Any ideas how this is typically done?

Also, I'm planning on connecting up the primary with another Deco via ethernet (rather than via WiFi). I think I saw something about changing the satellite Deco to behave differently if you connect it via ethernet? Not sure what mode or how to do it. 

Thanks