In a couple of weeks we are taking our 14 month-old on her first plane trip (Domestic, ISP-MCO.) To avoid any possible complication, we bought her her own WGA seat and will be using an infant carrier/seat (as well as signed her up for her own RR account). In preparing, what documentation/paperwork do I need to make sure we have with us? Since she won't be a lap infant, do we need to verify anything at the front counters or can we go directly towards the gates? Then what do we need to have ready for TSA and the gate? Lastly if the answer to the question is "birth certificate" does it need to be original, or is a copy acceptable? Unfortunately
this didn't seem very clear of what's needed in exactly what cases and what forms they can take.