I have Diono Radian as well, however i would not use it for 2 year olds
I have 3 kids, 6yo, 3yo, 1yo
Diono is too tall for anyone smaller than 3
It is tough to sleep in it while front facing in Tesla, it's too upright, and head does not reach headrest (not adjustable)
I have
Amazon.com : RECARO 2015 Proride Convertible Car Seat, Misty : Baby
for my younger ones.
Very comfortable