Split unit groups: can it be done?

Because I think it would enhance the game greatly, especially in simultaneous turns games where for instance you can only launch a separate fighter group every other turn.

Perhaps it might be done by allowing units to launch other units. Can it be modded or is it hardcoded?

It's silly not to be able to separate a fighter group into two wings (or combine two fighter groups into one) without going to a friendly planet/carrier.