OK, so i just got this email from dh's boss

2 x Safe-n-Sound Compaq Deluxe
1 x Safe-n-Sound Meridian (I think)

Compaqs on the outside, Meridian in the middle. They seem to ‘nest’ in together. 3 x Compaqs didn’t work as although most of the seat is smaller than most, wherever the widest spot is what matters.

I took the car to Babies Galore, after calling ahead, and just tried all of their seats to see what works. It is likely that 2 Compaqs and some other seat will be the best combination.

I hope this helps. Atleast new carseats are cheaper to buy then a new car