We should also note that Zigbee assigns a specific parent to each device, which Z wave does not.
That may mean the devices that were already on your network before you added the third reality plugs will not use them as repeaters.
If you want your existing devices to consider the third reality plugs as candidate repeaters, you have to “heal“ the Zigbee network, to get it to recalculate the neighbor tables.
Fortunately, this is easy.
First add all your devices to your network.
Next, take your hub, and only your hub, off power, including taking out batteries if it has those. Leave it off power for about 20 minutes. This will cause all of the other devices to go into “panic mode“ because they can’t find the hub.
When you power on the hub again, all the devices will rebuild their neighbor tables. This will potentially allow them to select new parents if new repeaters have been added to the network.
This process can take a little while, so you may not see results until the next day, but once it’s done, every device that can efficiently use the new repeaters should be using them. 