While i know you said you use FTL system, I would recommend using a system that lets you have conditionals in your casting macros that lets them work regardless of whether the toon is the master or not.
Not sure how possible that is to do with a FTL system.

Since I use a focus the leader system, and example of how i macro it would be:

/cast [target=focustarget,exists][target=target,exists][] Lightning Bolt

(i realize the abbreviation of "focus the leader" is FTL too, heh, normally just call it a focus system, but anyway, I assume by FTL you mean focusless targetless leaderless system, which is only useful in hardcore arena pvp)