Picking a family via a condition, then performing an action on another family that's also in a container doesn't work. Ashley said the bug goes way too deep, and probably won't be finxed until construct 2. I got around it by giving everything a pv 'uid' and checking that.
So one object per container would need a setup event:
for each sprite (blue family - picks the others in container)
- set sprite (blue family) value 'uid' to sprite.uid
- set sprite2 (green family) value 'uid' to sprite.uid
If ball overlaps blue
Green value 'uid' is equal to blue value 'uid'
Slightly more complex, but it works.