I currently have one HM-10 set to central mode and connected to an Arduino Uno, and two HM-10s that are set peripheral mode and are each connected to their own Arduino Nano Every. My setup works fine when I connect the central HM-10 to either of the peripherals individually, but how do I make the central one connect to both of the peripherals at the same time?
I understand this is a feature that was promised but not delivered. This might explain why you haven't found anything about this in your diligent reading of whatever datasheets you have, of which there are several.
You might be better off employing an NRF24 network.