So I’m currently pregnant with DC3. We have a BMW 320 and am looking for a narrow high backed booster that will allow an adult (me or DH) to sit in between it and a Joie Bold. We will put baby in front with air bag off. Really can’t afford to buy a new car just now as our car is less than a year old. Can I put the high backed booster in the middle so that the adult can sit on the outside? Our eldest will be 6.5 and is far too young to sit without any car seat. Please help 