Thanks for the "long way round" explanation. That was actually a pretty dumb question on my part. For some reason i was reading something else into what you posted. I should have known immediately what you meant by it.

In your custom formation; when you say you changed a unit's class from missile to skirmish and the formation was selected (defend); do you literally mean you changed 1 unit's class and the formation was selected, even though you had assigned that first block a minimum of two such units?