[Mobhack]

It's a simple case of which one is bought first. Deletion of formations in the middle of the list messes that up as it causes gaps in the unit list (an array). As does cross-attaching subordinates. In a scenario - you may well have to take into consideration the second side's deletions and reassignments as well. If you delete a platoon, then buy a company - the HQ can take that "higher" gap, and so throw the original numbering off as well.

The formation ID string (AAA999) is generated "on the fly" from the unit's position - it is not part of the unit's or formation's individual data.

So if you want a particular guaranteed formation order in a scenario it is really a case of deleting everything and then re-purchasing in the exact order you want, for side 1 and then side 2 as well.

cheers
Andy