Carseats on airplanes as checked baggage

I'm taking dd(1) and ds(4) on an airplane next sunday.
My question is regarding checking carseats. I'm worried that the baggage handlers will throw them around. Should this concern me at all? Could they be damaged, such as a carseat would be in a crash where you have to replace them?
Ideally I would like to carry on both seats, but I just don't see how that would work. I'm traveling alone with 2 little kids and I have a layover and am changing planes (both planes are the small jets with very little room in the seats for carseats anyway, and I broke my leg a few months ago and walking without carrying a ton of stuff is hard enough). It would have been another $450 to buy dd her own seat, so she will be on my lap, unless there is an open seat. DS is over 40 pounds so can just be in the airplane lap belt. None of my options are looking good to me and I don't know what to do! Any suggestions or ideas welcome.

Yes, having them damaged is a very real concern. Ideally you should never check carseats, and if you have to putting them in padding, either their original box or a padded carrier or something is next best.

What seats are your kids in? I would recommend getting two luggage carriers, or if they're in Britaxes Gogo Kidz, and attaching their seats onto those. That way you can put your kids IN their seats in the airports, AND carry them on board without actually carrying a pound. Ask for assistance once you're down the jetway, and definitely have your four year old walk down herself. I've had many attendants carry the seat on for me and put itin my seat, and once you're on board you can let your four year old move about the cabin while it's still empty (definitely preboard) because she can't get out the back and the attendants won't let her out the front, so you get some room to work. Check through all of your luggage except the diaper bag and whatever your four year old is bringing on board. You may also want to go out and get a padded bag so if and when you need to gate check your younger child's seat it won't just be thrown around.

What time of day are you flying? If you're hoping for an empty seat the early mornings and late nights are best, but if you have a layover that can be tricky because by the time your early morning flight arrives in your layover you then have a prime business person flying time. And at night you run the risk of an 8 or 10 hour layover.

Also, often you can get a pass for someone to help you to the gate in the original airport, and then from the gate at your destination. I definitely think you could get one, since you are in a bit of a pickle. That way your husband and whoever you're meeting can come with you and help with one of your kids. In your connection airport, though, you'd be on your own. Just make sure you have enough time between flights and you can take it nice and slow to get to your new gate, then just sit there until the new flight.

HTH

Wendy