Is It Possible to Have Me Sit in the Back Seat with 2 Car Seats?

depends on the size of the back seat. I've managed to shoehorn myself between my twin daughters' booster seats in the back of a '97 Honda Civic but would not recommend this for anything other than very short trips! But in my dad's '97 Accord, I could fit their old Britax roundabouts in the rear-center and rear-passenger side seats and sit fairly comfortably in the rear drivers-side seat. If you can fit the two carseats side-by-side your chances of being able to sit comfortably with the kids is better than if both seats are outboard (a friend in our twins playgroup learned this from the car safety tech who installed their Roundabouts in the back of their subaru legacy wagon)

My 3.5 year old is in a Britax Boulevard (behind the passenger seat) and my 8-month old is in a Graco SnugRide (in the middle). I have been sitting in the back (behind the driver) to keep my little one happy as she has been getting fussier in the car these days. I fit ok. I even sat back there on the drive back from LA. I suppose it would depend on the size of your car, too, and I'm not sure what will happen when my little one moves to a convertible. (By the way, I have found that my older one is very good at entertaining and soothing my little one, too, because they can easily see each other with the way they are sitting now--one forward facing, the baby rear facing. Not sure how it will be when they are both forward facing.)

I have two car seats in my backseat (One is a Graco and one is a Britax). Another person can fit in the back if there are 3 seatbelts. We only sit back there if we have a 3rd adult in the car with us. We have the Britax in the middle and the other car seat behind the passenger seat.

Other then passing out snacks, I never rode in the back with just one..
when we had 2, same idea, if they need a bottle I would give her one but otherwise they rode back there alone.

When #3 comes there is NO WAY I can even get back there.. bench seat 3 car seats no room for me :)

Until we upgrade to another car..

I have ridden in the back with the kids before with the two carseats. At the time we had one in the middle and one behind the driver. Now we have one on each side (the kids were fighting too much) and I haven't tried riding back there since we made the change, but assuming I could probably still squeeze back there if needed. It wasn't too roomy or comfortable back there when I did ride, but it was possible.