Two way linking of objects?

So I have an arrow that spawns and points in the direction of another sprite, linked to angle towards it based on UID/IID.

The only problem I'm having though, is not spawning duplicate arrows.

Is there an easy way to check if a sprite with a particular instance variable exists already before spawning?

<img src="http://i.imgur.com/IaqC7I1.png" border="0" />

I'd just use the uid instead of iid and uid. Here's a way to rework event 190 to stop creation of duplicates. The else is run only when there are no arrows paired with a pickup.

+circleBounds: on collision with BoxPickups

+For each BoxPickups

---+ArrGd: ThnUd = BoxPickups.uid

------ //nothing

---+Else

------- //your creation actions