Hi there!
I am right in the middle of coding a ESP32-based scoreboard for a leisure sport game. After having started off with just some buttons and an LCD display it has now grown to a main ESP controlling the logic itself and 2 "satellite" ESPs driving RGB matrix displays getting their data via MQTT.
My last idea now was adding a webserver to be able to alter the scores via smartphones from anywhere in the field. Async webserver is already setup and the main ESP is now working in AP+STA mode. STA is used for communication between the main ESP and the matrix satellites.
AP is reserved for client connections from the players' smartphones.
What came to my mind while giving the idea more thought was:
ESP is able to manage a max of 4 WiFi client connections at the same time. So in theory if you would have e.g. 4 players' smartphones connected all of them would be able to alter the scores via browser on their phone. So far no real prob.
Thing is, the further down the road the game is running the more beer is involved and users might even consider "secretely" altering the score to their team's advantage...
As so often, the more "leisure" a sport gets the more cheating is involved (with or without beer that is) 
Long story short:
Is there a way to get the respective WiFi clientID of the phones connected to AP?
I would like to use these IDs to create some sort of master/slave scenario so that only 1 smartphone is actually able to control the scores and the others are only allowed to read the scores.
As soon as the master phone is logging out another phone should become master (randomly).
--edit--
might even work by reading out IP adresses. Are the DHCP adresses issued in AP mode always the same? e.g. 192.168.4.2-192.168.4.5
--edit--
I know, pretty much thought for a leisure game, but...
Any ideas much appreciated!
Greetings!
Tom