Your carry-on gels, liquids and aerosols cannot be in a container larger than 3oz and all item must be able to fit in one 1 quart plastic bag. Any of these items larger than 3oz must be placed in checked baggage. If you try to take these items larger than 3oz through security they will confiscate/trash or tell you to return to your airline for checked baggage. For the milk, you should let the security screeners know that the milk is for the children, they may have to run a quick test of these liquids. Best to take the sealed packaged milk and do not open until you pass security, these types of sealed packaged milk/juice may not need additional screening. Make sure you take the plastic bag and milk out of your carry on and put separately in the gray bin.
Your carry-on gels, liquids