maybe I do not understand... but can't You do this with simple you pointer?
create next player and inside his action write:

you = ent_create("arrow.mdl",my.x,arrow_fun);
and then in arrow_fun in loop
my.x = you.x;
my.y = you.y - 250;

or in player action
my.skill70 = ent_create("arrow.mdl,my.x,null)
and in the same player action in loop
you = my.skill70;
you.x = my.x;
you.y = my.y -250;

Or I missed something