I have TP powerline. I have one of the pair, plugged into a socket under the stairs next to the main router. So we have an Ethernet in to a port in the router. I have the second TP powerline  upstairs in the spare room where it is plugged into a desktop PC. I would like to have another powerline in the front room so I can attach the PlayStation and TV. At present we are running a long Ethernet cable from the router under the stairs to the front room and straight into the PS4. The TV in the front room uses WIFI to connect to Netflix etc but the connection is really bad. Can I connect another powerline into this system? Can you just add more, or does it just work as a pair? If I can't find a solution using what I have I will need to buy something else. Ideally I'd like to keep the speed hence powerline.

hopefully there is an easy solution or purchase.