How do I pick instance using expressions?

I want to use drawing canvas plugin to draw a line from one instance of a sprite to another one, the canvas plugin requires x1,y1 and x2,y2 to do that, my instances have a variable "for" to store their order number (1,2,3) but i don't know how to do that for two instances of same sprite without creating any additional variables to store x1,y1 and x2,y2.

I tried using

Sprite.for = 1 ? Sprite.x : 0

Sprite.for = 1 ? Sprite.y : 0

Sprite.for = 2 ? Sprite.x : 0

Sprite.for = 2 ? Sprite.y : 0

But it didn't work...

I'm interested to see if anyone can resolve this because it looks like canvas will only ever pick the first instance

Use sub-events to pick different instances with different conditions, store the point positions in local variables, and then draw the line from the local variable positions.

You could use foreach (ordered) and local variables to keep track of the previous position.