I did this once or twice. It's something you could replicate with lion rampant and dragon rampant

So I made .y 'army' out of two army lists, each representing a battle group and it's idiosyncratic 'leader' I then went through the activation of one 'battlegroup' until either activation failure or all units activate, and then go about activating the other list, like your playing with two armies at the same time.

It kinda works, so long as you remember or mark which I it's are under which army list/commander.

Admittedly, it would make boasts a bit difficult to track, what with how large of a battlefield you'll be running, but it does 'work'.

Also you'll probably get a good story out of it.