What seats do you own?
I have:
Sunshine Kids Radian 65 (now called Diono R100)
Sunshine Kids Radian XTSL (now called Diono RXT)
Evenflo Triumph Advance
Britax Frontier 85
Safety First Guide 65
Graco SnugRide 30
Graco Affix (Elise is booster training!

)
We still need another booster (probably another Affix) and another slim convertible (probably another Radian) to make three across-es in both vehicles. The Evenflo is going bye-bye because it is so NOT a good choice for three across. The Snugride is going bye-bye in the spring as we're moving DS to a convertible. The Frontier will be our back up seat for DD1 and DD2.