It's a GREAT idea!
But I guess it's a LOT of work to copy & paste everything.
So I have an offer for you. CIV3_SBB can copy a frame anywhere in a storyboard, and it can ignore the transparent color.
So I think it could be easy to produce each unit individually, and then ask CIV3_SBB to "mix" several storyboard into one.
I can add an option to select the offset (X,Y), so a unit can be behind another, and a time offset (so the units do not all play at the same time, as in your animation).
With this modification, making multi units army for every units could be quite easy and fast. Contact me at this address
stephane.f.david@free.fr if yo are interested : it seems you already have some raw materials and ideas, I think together we can achieve a very nice solution.