recommendations for 3 seats/positions in 08 Sienna

We are expecting baby #3 in February and I am not sure how best to arrange the kids in the car with our current seats! Right now we have the passenger captain's chair moved over and ds performance sport in it with dd rf advocate next to him. This obviously won't work come Feb! We have a chaperone for the baby. My original idea was to take out the captain's chair dd seat is currently in and put her 3rd row center w/ baby 3rd row passenger but this will not work with the LATCH positions, not to mention in don't think the seats will fit next to each other! Of course I'm also thinking ahead to baby outgrowing chaperone and what seats will work. Ds has a huge torso and outgrew the advocate at age 2. Dd is 16mo and in no way following her brother's footsteps so who knows how baby will grow! Of course, safety is the most important thing. Oh and perhaps I should mention ds will be starting school just a few months after the baby arrives (year round school here starts in summer), so I want him to have easy access for carpool. I may be over thinking it all but that's just me I'm also not opposed to getting new seats if it will help (except the performance sport, it's staying!)

I took out the pass side captains chair of my Sienna and LOVE it that way. I have three kiddos as well and pretty much once #3 arrived that captains seat has been stored.

If i were you i would put the chaperone in the remaining captains chair (placed on the drivers side), put your FF in the pass side of the 3rd row outboard and then install your other RF seat for your middle child outboard drivers side with the seat belt. That leaves the middle seat in the 3rd row empty for the middle child to climb up and into their seat. Plus that allows anyone helping at the school drop off line easy access to help your DS get out/in.

You will be amazed at how much room you have to move around in their for the kids to get into their seats and for you to climb in and help them as needed. Occasionally we cart around an extra child or two and putting that other seat back in makes it seem SO crowded