I'm a little confused by what macro's you're trying to go where, so... I think you are trying to push "1" on your main to do one thing, and "alt-1" to make only your alts cast the spell. Assuming you're using the focus to target your main, the macro should be something like:

#showtooltip
/focus 'yourmain'
/target [target=focustarget]
/cast [mod:alt] [exists,harm,nodead] Holy Fire

At work atm, but I think that will do what you want it to do