Do any seats fit these criteria, or are we going to have to buy two seats? At the moment we have the Maxi Cosi Pebble. We use it with the isofix base, our nanny fixes it with seatbelts. This works really well. Is there anything that will do similar for the next stage? All of the rear-facing Group 1 seats I have looked at seem to come with a fixed base as the only option.