IP Scope

I would like to add certain devices onto certain eeros.  I have a 3 PK and I have 2 downstairs and 1 upstairs.  Downstairs, I have several smart home devices (includes 1 eero as my gateway and the 2nd plugged into my ADT Pulse that I cannot unplug) and I have a few devices upstairs that are connected to wifi.  I would like for me to dedicate my 2 Roku TVs that are upstairs to the eero that is connected upstairs.  OR setup a scope of IPs for each eero and that way when I make a reservation, it will always have the same IP and always stay connected to the upstairs eero.   Thanks