Congratulations
@Mbuondelmonte. Kids are fun, they take a lot of work, they get the most sleep in the house, at moments they frustrate you beyond what you thought was frustrating, they'll be the most expensive things you ever "own", but they're a lot of fun.
How old are your two kids now and what type of car seats will they be in once the 3 newborns arrive?
We currently have 3 kids; 5, 7, & 8. They're all pretty close in age where all of them are each in some sort of car seat all at once, some of them take a lot of space. My '15 Yukon XL Denali has captain chairs in the 2nd row and it works well for the 3rd kid to just walk through to the back and get in his own seat.
However; I'm currently in a '21 Yukon XL SLT rental vehicle and the 2nd row is a bench. My 7 year old son rides in the 3rd row and he is in a convertible car seat still. For him it is easier for me to leave the 3rd row split folded, the area for his seat is up obviously and the other half folded. It's easier for him if I open the tailgate and he crawls in through the back that way than to crawl over the 2nd row bench. Thats with (2) car seats in the 2nd row; A booster and a convertible car seat, nothing in the middle.
This seating arrangement will be tough with the (3) newborns. It'll be a challenge.