You can also use for each.
The collision will act as a filter, if you do the for each after the collision condition. You can then use loopindex to pick in actions.
+>Sprite on collision with sprite
->for each sprite sprite set value to loopindex
Then there's also picking by position(closest).
+>Sprite on collision with sprite
->sprite pick closest to 0,.y
-->pick closest to .x,0 do stuff
->sprite pick closest to layoutwidth,.y
-->pick closest to .x,layoutheight
That works since usually two object don't occupy the same xy on collision.
Edit:
Didn't read Tula's last para, so yeah what he said with loopindex for good measure.