@Bulkhead 

Here in the US region, the TL-WPA8630P was never sold individually but in kits, I suspect it may be the same case in your region as well. You could probably reach out to your local support team for confirmation.

However, the powerline devices use the HomePlug AV2 standard so if another powerline device uses the same standard then it should work.

@Tony 

Thanks Tony. Looks like I'll have to purchase another kit and hope it's compatible. Otherwise I'll just two independent systems and some redundancy.

Rob

@Bulkhead The powerline system is a standard, so brands can be mixed. I currently have TP-Link devices plus two other brands, all working together. So, use whatever you can get. That model you have is AV1200 spec, so for best results when getting another brand is to match that it is close to AV1200 such as AV1000 or AV1800.

@magarity 

That's excellent news. Thanks for the input.