I have 2 boys, 4 and 2 years old. They are in harnessed seats everyday. I'm looking for a hbb to keep in my mom's car for when she has to occasionally pick up both kids at the same time. She has one harnessed seat installed but picking up both is often on short notice and I can't install a second seat for her properly every time. DS1 would probably use the hbb once a month or less. I'd like something safe, easy to use as my mom has carpel tunnel, and would last us a while. What are my options?