Ok so ds2 (13m 23lbs 28in) is right at the one inch mark on his chaperone (with cloth diaper) and needs to move into one of our convertibles. Currently DD is also RF at 3.5 32lbs 38in. We currently have a MA70, RA 50 Classic, CCO, MR and Onside Air. They ride in both our cars almost an equal amount of time and both fit in all seats RF besides the CCO. So I guess my question is with only 3 seats with RF rebound control options witch one would you put in the non rf tt seat, the heaver older child or the lighter younger one or whatever is there and not worry about it? I am aware that I may be over thinking this!