If you have two kids in car seats, how are the seats situated and what are the ages?

When c was in her infant seat we had her in the center position, since it's safest and it fr best between the front seats that way. But we got a bigger car and have her convertible RF behind the passenger seat now. I figure when baby 2 comes we will have the infant seat behind the passenger and the convertible FF behind the drivers seat. But I see people talk about having one in the center, which seems like it would be hard to buckle and like my older LO might whack the baby with a toy or drop snacks in the baby seat...

(c will be about 28 months when new baby arrives).