@staveled 

If you are happy with your current setup, I would suggest keeping it. Get Deco M5s, wire them to your powerline adapters, and Deco units will think they are connected to Ethernet and should be able to use Ethernet backhaul. General questions about Ethernet Backhaul feature on your Deco.

Same TP-Link brand for both Deco and your powerline adapters, so unless TP-Link support says otherwise they should be compatible. You'll keep your home network as is, and will add WiFi to it.

I tested my Deco M5 with different brand of powerline adapters and they worked together just fine.

I would recommend running Deco mesh in Access Point mode in that setup. What’s the difference between Access Point mode and Router mode on the Deco?

  @Alexandre. 

That's perfect - thank you.