I have a 15month old and a 5 year old and have only been able to fit 2 car seats in mine, there is only a few inches between them. There just isn't enough real estate to fit a third, nor is is safe to do so. There are only 2 anchor points for car seats anyway. Don't gamble on safety, you need a different mode of transport for them. Sorry.
2006 SE 6 Speed, Solar Yellow. Zone 2" Hydro BB, Sway Links, and Steering Stabilizer. 31x10.5-15 Bridgestone Dueler AT Revo. Alpine CDA9813, Polk MM6, Polk C400.4