I currently have a netgear nighthawk AC2600 and 4 tp-link av1300 powerline adaptors.

The powerline adaptors are used in remote places, (loft & garage) to connect raspberry pi's via ethernet, and one behind tv cabinet for TV, playstation, firecube etc.

I also have a philips hue and lightwaverf hub connected directly to the router.

I was looking at a mesh system and was recommended the Deco's but I wasn't sure if i could use the P9's that use the mains for backhaul and retain the existing powerline adaptors?

So it would be :

ISP ---> cable --> Router (in modem mode)--> cable --> Deco P9 --> mains/wifi --> additional Deco P9's

                                                                                            \ 

                                                                                             \ --> Cable --> AV1300 --> mains --> additional AV1300's

I can use the 2nd ethernet ports on the Deco P9's to plug the Philips Hue & Lightwave RF hubs in elsewhere.

does this look feasible? 

Many thanks,

SeanC