Car seat advice

[Firefly131]

Hi, we have number 3 arriving in a few weeks and I'm stuck on how to arrange the car seats once baby arrives. Can anyone share the order they have 3 car seats in the back? Who goes in the middle? We have an S-Max so 3 ISO fix seats, I'm just not sure where to put which seat...
we'll have a maxi cosi pebble, a pearl and most likely move our 3 year old from his pearl to the next stage car seat.
Also any advice on which car seat to get for 3 year old would be greatly appreciated!
Thank you!

We have an s max too with number three coming anyday. We have pebble and family fix base , axiss and rodifix all maxi cosi for our soon to be newborn , 2 & 4 year olds. Because of the age of the s max we have it only has isofox points on two back seats not the middle. So we are having newborn and 4 year old on the two outer seats and 2 year old in axiss in middle all on back row

Thank you! That helps. I'll have a look at those seats too!