3 kids fit fine in the back, but I'm not sure 3 car seats would. Sucks that you have to get rid of your JK, but I'm sure you'll be back in one as soon as one of your kids is out of their seat and you can make it happen again.
Good luck with the sale and congrats on the new addition.
Before you sell it because of car seats ..... look at the "sunshine kids radian" car seats ..... we can get three kids across in a XC90 Volvo. Currently we have two radians with a baby carrier in the middle.