Is there some kind of rule that says the Axis units can't merge on turn 1? I couldn't find it. Here's three units that supposedly belong to each other and they can't merge.
EDIT: Maybe they have to have not moved yet in the turn?
Merge is different than building up 3 regiments of the same division into the full division. Merge is when you want to disband a weak unit and put it's resources into another unit.
All understanding comes after the fact.
-- Soren Kierkegaard