If the other driver is considered At-Fault in the accident then the car seat should be factored into the total amount of damage caused by that driver. Assuming the total damage doesn't exceed the amount of coverage on that driver's policy then you should be compensated for the loss of the seat plus the other damage. If you happen to be At-Fault in the accident then coverage for the car seat will be up to your insurance company even if you have comprehensive
and collision coverage
on your policy. There could be stipulations concerning occupancy of the vehicle at the time of the loss and whether or not your deductible would apply. It would be best to consult your company to inquire about the specifics of how your policy treats the coverage of car seats. Best of luck!