I am uncomfortable putting a backless booster next to a high back booster or forward facing harnessed seat. I have imagined fears of the backless booster rider's head hitting the side of the cr next to it. So I have avoided that. But now my oldest is too tall for high back boosters and my middles still need them. If money was no object I would buy that cushioned britax thing. But money matters right now. What advice can you offer me? Am I being silly? Should I avoid this set up if I can- taking a different car, for instance? Put my middles in a backless booster if it fits them? This is just for my dh's car, which they rarely NEED to ride in.