Options for car seat arrangements with 3 children

Hi everyone,

I am asking for advise in relation to Car seats.

What is the best way to go when you have a 3rd baby?

when our 3rd baby is due our oldest boy will be turning 5 and our 2nd boy will be turning 3.

My intention is to use an isofix/Maxicosi pebble for our new baby but I am wondering what is the best thing in relation to fitting 3 car seats into a VW Passat? 

OR is the only safe option getting a people carrier/space wagon?

I actually really like my normal car but I don't mind if I have to change if it's safer.

Also, has anyone used the Multimac? Is it a viable option?

Any advice would be really appreciated x