There are certain combinations that would probablywork, but you'll likely need all new seats.
3 Radians probably wont do it. even though the seat is the narrowest per se, what happens is that some seats, which are wider overall, can overlap and therefore you can fit 2 larger seats together in a tighter combination than 2 narrower seats..does that make sense?
I am pretty sure you can 2 FFing radians outboard with a RFing Titan in the center. A my ride might also work in the center, which would give you a taller shell and more weight rearfacing. I got that combo to work in my friends caravan, and i think the rear rows are basically the same.