Well, lets see if I can help you out. 1st. log onto www.tsa.gov web site to get the most accurate information for traveling. (bring a copy with you if airport security - says no & the web site says yes- they are not always up todate in all the airports) a 2nd, I assume you are traveling domestic not out of the US. (if out of the US, then the playing rules change some) Domestic travel: You may bring on formula, May I suggest the individual packs sold at Babies r Us. You are limited to liquids going through security, but since you have an infant, that allows you to bring on additional items. 3rd. Make sure you give your self 2 hours at the airport traveling with kids, the stress of getting to your plane on time w/ bags, kids & carseat is a mess. Bring your stroller, a good one. use it to carry your carryon's through the airport. Your daughters will be helpful but if you have a long walk, ask for an electric cart to take you to the gate & baggage claim when you arrive. I am not sure the type of plane you will be on, but most planes have hot water & bottle water to give. Movies & music are offered for free/ or a cost for the head set, bring your own & save the money. Look on your airlines website to find amenities offered. Remember each plane is different so you can call the airline & also reconfirm your departure time & seats assignments a day or two before you leave. Check in on line saves time too. Some airlines offer food to buy, but it is not always the best for children. I recommend, packing pre made meals. No jello, or pudding. For early am flights, I bring dry cereral,(they have milk), just place it in tupperware & bring some extra plastic ware. I make scramble eggs & bacon keep it in tupperware too. You can bring on sandwiches/chips/snacks etc. I also like to bring fruit, Oranges, apples,carrotts& veggies, (buy ranch dip at the airport, It is a liquid) keep your softer fruit in a tupperware, b/c packing items in a bag it is going to get smushed. To take some prep work off of you, You can purchase food at the airport & bring on the airplane, it will just cost more. You can also purchase additional water at the airport which I recommend to keep you & your family hydrated through the flight. If your 10 month old has a seat assignment, not infant/lap bring your car seat, try not to take him out during the flight much, b/c it is safer for him to be in the car seat, then in your lap. A Window is the seat you will need to place the car seat. If you are checking your carseat/stroller at curb side check in, some place charge, or just a tip is suffecient, ask for a large clear plastic to cover your baby's items, you might have rain or snow when you land. At this age children travel extremely well, it is when they are 2/3 & they don't want to sit or they are exhausted & won't sleep from excitement. For older children, stop off at the dollar store, pick up items that it doesn't matter if they lose them. But only give it to them on the plane after the flight has taken off. & remember to save a few items for the trip back home. You can bring game boys, dvd's ipods, laptops ect. make sure you have back up batteries for extra long flights. Count your bags write the the number on your hand, total & carry ons. Tag all your items inside & out. If you lose the bag & the tag comes off, the airline will look inside for ID. Remember where you parked b/c in a week you won't.
****My most important advise is ask you peditrician if your 10 month old can have any benedryl or something for his ears, you never know when a cold might be coming on & his ears could have blockage, which is the worst for anyone, they have childrens chewable too. Give it to him when you board the plane, should be about 30 mins before take off. Also during assent & decent have a bottle ready for pressure relief. If none of that works, pull on the ear gently to try to massage the tube to release the pressure. I have seen grown men in tears b/c of the pain. Not to scare you, just to inform. Planes do have changeing tables in the bathroom. Just remember the small bottle of hand santizer. In advance try to schedule early flights for children, they seem to travel much better when they have had a good night sleep. It is not easy on you, but you will appreciate it when they are more relaxed & you can grab a nap on the plane, - Don't forget your neck pillow & extra blanket. Good luck from a mother of two preschoolers, a flight attendant of 14 years. PS I have traveled many different airlines & have not been charged for checking a stroller or bag at the jetway. Have a wonderful trip!