Here is how I do it:

Create 4 ATG:
Up
Down
Left
Right

I leave them empty to begin with.

Under my Repeater Regions Keymap Set I create 6 Keymaps. The reason I create them here is because my Toggle Keymaps Key that loads and unloads my keymaps does NOT turn this Set off.

Clear Movement ATG:
Action Target Group Action - Delete All out of Up
Action Target Group Action - Delete All out of Down
Action Target Group Action - Delete All out of Left
Action Target Group Action - Delete All out of Right

I then create 5 Keymaps called 'Slot X is leader' where I increment the Slot Numbers.
The actions that take place in this keymap are:

Do Keymap Clear Movement ATG (This empties everyone out so it cant fuck up)
Put SLOT2 in UP
Put SLOT3 in DOWN
Pput SLOT4 in LEFT
Put SLOT5 in RIGHT

In the remaining Slot X is leader keymaps I simple replace whoever the keymap is about with Slot 1 eg Slot 3 Is Leader would look like this:

Put SLOT2 into UP
Put SLOT1 into DOWN
Put SLOT4 into LEFT
Put SLOT5 into RIGHT

Under my 'General' Keymap set (this keymap IS turned on and off by my toggle key) I create a Keymap called 'Spread Out'.
It simple does this:
Keystroke Action send W to Up
Keystroke Action send D to Down
Keystroke Action send A to Left
Keystroke Action send D to Right

I tick the box that says block all other actions while keystroke is held. I bind this to Numpad 0.

Under my character set I activate the radio button that says when I switch to this character DO THIS MAPPED KEY and select Repeater Region : Slot 1 is Leader for Slot 1 and rinse repeat for the other slots.

So now everytime I switch to a different character using my hotkeys regardless of wether I have keymaps or broadcasting toggled on or off, it deleted everyone out of the ATG's for movement and rebuilds it each time.

My spraed out key simple sends the key to whoever is in the various groups at that time.

Hope that makes sense. I can tidy this up or talk to you on vent about it.