first let me say congratulations mate and then get straight to the the advice.
easiest (and in all practicality, the only) way is newborn in the middle .you simply cannot put the baby seat behind a seat unless the person sitting on that seat is 5'1" or willing to squash their face on the windscreen and crunch their knees. with the second the best spot is behind the passenger.
that way you have the most room with the rear facing seat and the closest eye on the other kid who is effectively boxed in
i'm fricked if i know what we're gonna do come late december though with the 3rd cub on the way
no......really.... i'm lookin' for suggestions here

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I spend most of my money on booze, fast cars and women, I just waste the rest...