4 kids, big dog, vw touran

[Headlesshorseman]

So we are ttc baby no 4 at the moment. With all going well by the time it comes we will have dd14 ds12 dd4 and a very big dog. With all the kids we have used Britax first class and kept the seat in the car (the other car is a golf so used for commuting) with a lie flat pram.
But. Pram is dead (I think 3 DC killed it). We have a big 3 wheeler for dog walking, but it's not from newborn.
So, practically, how do I fit everyone in the car, and which pram do I buy that can fit in the tiny boot once all the seats are up?
Or do I start saving now for a minibus?
And can we really manage with just 1 big car?

We only have 3 and a dog but we have a city mini pram which is great for folding (one handed) and fitting into small spaces (plus wheels come of easily if going on holiday etc and need more space). It's also good off-road and one handed steering.
Our dog Is in a cage which helps with fitting things around her. I think we could fit 4 in our smax day to day but not for holidays.

Thanks. Dog is too big for cage now so sits on a seat with harness (large retriever). I love the city mini 😁
Is a roofbox for pram practical for every day use?

We have a maclaren xt which lays flat, we used from birth but is a tidy umbrella fold. Would that slot between the seats if you put the middle one in the middle row down? I know it fits lengthways across the boot but not if any of the rear seats are up.