In fact Sonos doesn’t officially support powerline adapters. The connection is too variable in quality. That said, many do use them without problem. See how you get on.
The main issue however is that having wired one of your Play:5s the system will flip over to SonosNet (‘wired’) mode. This means that all the other speakers will try and connect to it, so you could suffer problems with them instead.
There is a solution to all this, which is to force your system into ‘mixed mode’.
To do this you’ll have to wire both Play:5s (and yes, you can daisy-chain one off the other) then go into Settings/System/[room name]/Products for each of the units and ‘Disable WiFi’. It’s confusing nomenclature, as you’d actually be disabling SonosNet. The Play:5s will then no longer try to ‘capture’ the other speakers, leaving them free to remain connected to the router.
You can see how everything connects in Settings/System/About My System. WM:0 means wired or SonosNet. WM:1/WM:2 means WiFi.