Ok so we have mesh wifi setup in our house using TP-LINK Deco X50 Multiroom Wifi system with Ethernet backhaul. 

Using a Powerline adapter, we have been able to take a line out to a standalone garage. This is connected to an old TL-WR740N router which gives us wifi in the garage. However it is a different network to the mesh wifi network in the house.

Just wondering if it's possible to setup the TL-WR740N so that it all becomes the one single network. If that makes any sense.

Thanks in advance.