We use our seats the way Krist mentioned. The 3rd row seats are suitable for kids ranging from 4 - 12 years. I think if your kids are in that age range that car seats aren't necessary, but not 100% DD2 is 6 & with her half seat booster is too tall. So not sure that anchor points can be fitted. You can fit them to the floor at the back though if needed.

We have DD3, 2nd row middle, DS 2nd row passenger & the second row drivers side seat is folded down. The older kids sit in the back.

For long trips there isn't much room. & if the back seats are down there's not much room for a pram. I kept my tandem pram on its side in there.
But I only need the extra room for long trips. Any time I need boot space, the older kids are at school, so the 3rd row is folded up. Mine sit up against the back seats, not on the floor, so all the boot space is still there.

If you like I can take some photo's tomorrow to show you how ours works & email them to you