We relied on a car seat in Orlando when our son was 9 months old. Basically, all of the seats were piled in a large bin ranging in size from infant carrier to high-back boosters. All had been cleaned and were in clear plastic bags. It was up to us to find one that fit but there were plenty there. They have to put the disclaimer b/c of unforseen circumstances (i.e people delayed in returns with seats) etc. Unlikely they would not have seats. I would recommend bringing your own if possible though. Just easier. If you are paying for seats for the children on the plane anyway, take them on the plane (have to be window seats I think) as long as they are FAA approved. We took backless boosters in a carry-on last summer as they cannot be used in airline seats but we were able to stuff items around them and carry them in luggage.
