Yes,you can add similar PLC product in your network.
You can pair the new one in the same room with your existing PLC.
Then put it where you want.

Hi, Just a question, Is your router wireless with a lan hub..???
If so why have you the bigger unit pluged into the router, I assume you have it located close to the router..??
I assume the bigger unit is the TP-link with wifi.

I have the same kit but I connected it the other way around, The small unit located beside the router and LanPort plugged into the router hub and the larger one plugged into a power point in a remote room so it gives me wifi and LAN in the vacinity of the remote room and devices near the router get wifi from the router. That gives me strong wifi signals at the remote room from the TP-Link where the router wifi was weak and strong wifi from the router for devices near the router. The small units only give a LAN wired point anywhere one is plugged into the power circuit.

I too would like to add additional PLE's to my WPA281 however I can only find 'kits'. Could someone please point me to suitable units in the UK?
Many thanks,
Abdy

Single Powerline with WiFi are available dabs.com and BT shop £24.99, buy within UK. The WPA281 Version 3 is available. If you stay with TP-Link, I think most units are compatible, ie can be paired to any of your existing powerline units and Wifi cloned to your router.

I posted on another thread to see if anyone could confirm what models of units are compatible but no replies......this whole forum seems to be very slow with un-responsive users...?????