With my first she was in the middle, when number two came along, she was in the middle in capsule and dd1 behind passanger front faceing, then when they were older had on either side, for my sanity.

Now with dd3, have dd2 behind passanger in maxirider(booster, dd1 in middle and bub behind driver still in unity capsule at 15 months. Rational was the older two get in and out on their own and I wanted them getting out on the kerb side. I get bub out so can look out for cars etc.