You can't change a helper's parent, parent's the thing that created the helper (or root, i know they work in a similair way but i don't know what's the difference, so you should look it up), as simple as that.
What you want to do when you want to get a helper's variable is something like this
trigger1 = numhelper('put the id of the helper you want to use here'), var(5) = 1 (you can simplify it by not writing the "= 1" part)
This code will get variable 5 from THE helper, what you were trying to do was to get variable 5 from the character itself (in other words: you)