Here are two problems:

1. You are using the same modifier-combination for Voon and Lycoon (alt + shift), this need to be different.

2. What you want is not easy to achive, because you need the modifiers alt,shift,ctrl to identify which toon is leading (because you are using more than 3 toons, and there is no combination for the fourth toon, what you found out...).

What you can do, in theory to achive the above is using a tool which can correctly differentiate between left/right alt/ctrl/shift and define the modifers for your toons like this:

Malerick = lAlt
Nubork = rAlt
Voon = lAlt + rAlt
Lycoon = rAlt + rctrl

now shift is 'free' and you could use it for the 'cast on focus'. (Btw. HKN is a tool which can do this).

On short question at the end:
Wat is the reason you need the 'cast on focus' in your follow and target macro?
What I don't understand here is, what you want to achive by this. -Could you describe what you want to happen when you press the 'cast on focus'-modifier and the follow/target macro?