Flying longhaul next month with DD 13 months, she has her own seat booked and we are considering taking her car seat on board as thinking she might be more likely to sit nicely in that (probably wishful thinking but we can but hope). Has anyone done it? Is it worth lugging it through the airport? The seat is FAA approved but it’s just under an inch wider than the airline seat. Will we be allowed to put the arm rest up so that it fits? The airline’s website isn’t clear, google suggests it will be allowed but most results are 5+ years old. It’s AA main cabin extra and the seat is a Britax Marathon in case that matters. TIA!