Schema of a Smart Home: One IP => Multiple MACs

I'm not sure how much more "messy" things could get when we already have 2 MAC addresses assigned to the same IP address?

For example, the EX8000 shows:

Now, what would break if the router allowed for a reservation table that had the same two MAC's for this single interface? If NETGEAR cannot share this info between the EX8000 and XR700, then just let me type it in myself and leave the responsibility with me with some words of caution. We all know that only one of these MAC's will show up on the link layer at any given moment. And, it's not like there is fencing put around every place users could mess things up on a router!

I used the term statically-addressed which was confusing - apologies. I only seek a dynamic DHCP assignment of an IP via some IP reservation mechanism. There is no static IP option on the Kasa smart plug (I would want to manage addresses centrally, anyway) and I do not want to use a smartphone app to operate plugs manually. Instead, I want to automate an "on" command for a pump when a container is getting full using a Node-Red interface. People like to automate stuff like this and are hitting this issue and building their own dnsmasq or moving to DD-WRT or proprietary mesh rather than leveraging existing standards and asking vendor to fix what they have broken.