Flying with breastmilk

We are getting ready to fly home to see family. We are excited to have babysitters for once but I ebf and don't have an oversupply. I would like to bring some fresh breastmilk back with me to have on hand when we get back. I will pump too but don't want to spend a lot of time pumping and I only can pump a few ounces at a time. I plan on packing the milk in the little cooler with an ice pack. Is it better to travel as carry on or put in luggage? Where would it stay the coolest? I know milk in a cooler in good for 24 hours. It will be in a cooler for about 10 hours then I plan on putting it in the fridge. Will it still be good for a few days refrigerated? Or should I feeeze it when I get to my destination? Any tips appreciated! We live over a thousand miles from relatives and are really excited to be able to catch a movie or go on a date while our little girl gets to spend time with her grandparents.