Third child

What car do you have and what ages are your kids?

Look into slim carseats! If you google "slim carseats to fit 3 across" you'll see a few different options for different price ranges ❤️

I would visit a specialised car seat retailer to try some options. You can also look in some FB car seat groups and search for your car plus 3 across and see if anyone has managed it. I like the bump to booster group.

But if it's only on the weekend, I would have the newborn rearfacing in the front with the airbag off, and the other two in the back, and the other adult in the middle seat in the back

Do you have a second car? You may need to go in two cars on some occasions. Or look into the slim carseats. It will be hard. Expect lots of broken nails

If you’re US based you can check out safeintheseat. They have a quiz you can take to be matched to a car seat that works for your car and budget. One section is for slim car seats to fit three across. It might be worth trying to have baby #3 in a convertible seat from birth if that’s an option for you.

Put a rear facing child in the front with airbag off, if you can’t do this then I would suggest getting a car with 3 full sized seats in which the car seats can fit on, otherwise it is not safe 😁

I defo don’t think you’ll fit 3 in the back even with a slimline seat as it’s not a full sized seat and could be dangerous trying to squeeze one in where it doesn’t fit properly. I think your best bet is the infant carrier in the front with the airbag off but then your issue is if you’re traveling with 2 adults. I take it changing the car isn’t an option at the moment? x