@Der:
…
When you replace the units, do you put them back where you got them from or does it have to be at your factory?
You just replace the units where they stand.
@Der:
And if you place them during your purchase phase, doesn’t this mean they can effectively move 2x in the same round? (USA moves transport of men to Russia on USA turn. Russia converts men during purchase phase. Russia can then move men in combat phase on Russia turn?)
Not really. Converting units is not moving units. As Russia always starts a new round, the allied units that are to be converted have moved (at latest) in the round before. In your example it is true that they move in two successive turns (USA then Russia), but these turns belong to different rounds, and those units still only move once per round.
Best, P@nther