we are travelling for a couple of weeks in a motorhome and I am trying to find out the best options for child car seats. Kids are 4 (20kg) and 2 (12kg). The company doesn't rent them but says we can buy them/ rent them nearby. I just don't know what kind I need to get - someone on here recommended Maxi Cosi Priori but the woman in John Lewis thought it couldn't be used with a lap belt. Has anyone done this? Starting to be concerned about it.