I'm in the process of redesigning my setup and I'm struggling to implement the follow process.

When I mover over a specific region(button/menu etc) I want to send a modified key to a specific character but the standard key press is sent to all other characters. i.e ... so I'm spamming the 1 key, as expect all characters are receiving and pressing the 1 key but when I mouse over a specific part of Character B's health bar I want to send CTRL+1 to Character B only. All other characters will continue to receive and send the unmodified 1 key.

I was playing around with a menu but this doesn't appear to be the correct approach.