Adding 3rd (wired) Node to R8000 & EX8000 Setup for 3 total wireless access points

Hi All, I'm hoping someone can help me. I'm looking for advice on how to add a 3rd wireless access point into to my current system. My current router is connected wirelessly to an extender, but next I'd like to add another access, but make it wired. Ideally, I'd also be able to control everything in the Netgear Nighthawk app. 

Any suggestions?