You can use modifiers with your keys.

For example, if you use the mapped key wizard...
You can use a hot key of Control + A, and have it send whatever you want to the game.
Which doesn't have to be Control A, but it could be.
You can have a macro bound to act on the Control A input.
In a lot of games you can add additional action bars, and often have those bars hidden so they don't clutter your screen real-estate.
The hot key will still activate the ability.

You're not limited to Control, and can also use Alt or Shift quite easily.

Modifier keys sometimes don't interact properly with the numpad keys.
But they work fine with the numbers above the alphabet keys and of course with the alphabet characters too.

You can use mouse buttons as hot keys, especially if you have a fancy mouse like a G700 or something similar with a lot of keys.
In general its good to use the mouse as the hot key, but have a key combination sent to the game.
With something bound to that key combination.

You can use a combination of modifiers, such as Alt + Control + Whatever.

You could also use another key, as a modifier ability.
Make an entire key map, similar to Control/Always On or General.
You'd have a two-step mapped key, which activates on press or release.
When you press the key, or more specifically while you hold it down your alternate keymap is on step one.
Which deactivates your 'normal' keymap and activates your 'alternate' keymap.
When you release the key, it reverses the activations so your alternate keymap is turned off and your normal keymap is enabled again.
That way, your 1, 2, 3, 4 etc... can do a normal action most of the time, but act entirely differently while you're holding down a specific hot key (which might be a your mouse's side button which is pressed by your thumb.



If your game is world or warcraft, or something very similar in mechanics.
You can set Click to Move to be on (escape, interface actions, mouse actions, check the box).
And have an Interact With Target hot key set.
Then you target the corpse with the lead/active character.
Everyone assists, which could be your 'cast whatever kill key', which won't fire off because the target is dead... but will still make the other windows/slaves assist your active character.
Then broadcast the IWT key a few times... might need to press it once/twice to get the slaves to move into range of the corpse, and then again once they're stationary and near it.
Sometimes I needed to push it once per character.
But eventually they all loot the corpse and each take what they can from it.

You can use this exact method to interact with a flight master or with a quest NPC.
Mouse broadcast (or the Jamba addon, if you're playing Warcraft), can have your slaves pick the same option as your active/master character.