Wouldn't it be easier just to have 5 separate keys for target specific chars.
have one key
with the macro
have all chars names of one account thereCode:/target some char name
/target some other char name
...
do this for all 5 accounts
then setup another set of keys for greater heal shield ...
that way it takes 2 key press to do any combo
then when yeh add another char all yeh gotta do is add em into the /target macro