@hotwired 

You will only need one powerline adapter wired to your router. The rest can be placed around your residence so with the new kit you have, both adapters can be used as if they were the "second" adapter, one for wired only connection, the other for a Wi-Fi access point.

Tony, 

To be clear, the AV1300's only have ONE ethernet port and DO have antennae, presumably to plugin the router, then broadcast the signa.. The companion had NO antennae and 3 ethernet ports, presumably because it's intended to be the receiver and you can plugin up to 3 devices. I'm assuming there are no antennae because it's intended to broadcast only a short way, where it's an extender. So right NOW I have the AV2000. BOTH of thes look exactly the same, and yes, these are intended as "one receiver one transimitter and it doesn'w matter which is which"

So MY plan is to REMOVE the AV2000 as transmitter (because one of the AV1500s CANNOT be used as receiver, that is the one with antennae and only one ehternet port). Then I'll use that "antennae'd AV1500 as transmitter, then the other AV1500 and both AV2000's as receives. Does this make sense?

@hotwired 

With the powerline devices there is no "transmitter". All you need is just one powerline adapter wired to the router, which ever you choose is entirely up to you as any will work. Typically the one chosen is the one that is only wired (no Wi-Fi) for obvious reasons. 

What you mentioned will work fine.

Fantastic. As it turns out I returned the AV 1200 and am going to buy another set of the av2000s anyway. Thanks so much for all your advice.

@hotwired 

You are very welcome.