To pair your detectors with sprites, make sure there's the same number of detectors as sprites, then do this:
--- Detector: Set position to (0,0) from Sprite
MMF automatically pairs the objects. Think of MMF like a giant object database (which it is pretty much, with conditions acting like a query). Multiple object types will line up in 'rows' inside MMF's logic, so if you have the same number of objects of each type, they'll all follow each other.
This is actually how Spread Value itself works.
If you want to transfer data between these objects (the sprite and detector), try keeping the same alterable values in each.
Then transfer them across using always commands, e.g.
--- Sprite: Set 'Some Value' to 'SomeValue("DETECTOR")'
and so on for each value you want them to share. This makes sure your Sprite always carries with it the same info that the detector carries, so it can then do tests based on its own vars, rather than having to keep asking the detector what's going on.
It'll preserve your object pairing as a matter of course, thanks to the 'row' effect mentioned above, and it's pretty darned quick too
As an interesting note too:
If you have 2 of object A, and 10 of object B, and you tell B to follow A (i.e. the many must follow the few), then...
...Both A objects will have 5 B objects following them. Interesting, nÚ?