This is not necessary for Disney. I suppose if you're travelling internationally then it might be a good idea but it's certainly not needed for any domestic airlines or WDW. I do keep our medications in their original prescription containers when flying (domestic or international) though for pills that isn't even necessary (for liquids or needles it is important to be in an original prescription container).
With ADHD kids or adults and flying internationally you need to check the laws of the country your flying into. Some do not allow controlled substances into the country even with prescription without jumping through considerable hoops or being detained for a few days. Each country is different, some baulk at stimulants, others pain meds etc.
Just an example
A few countries are particularly vigilant, if only about certain drugs. Greece and Turkey frown on opiates like codeine, while Japan gets riled up about stimulants. The Japanese embassy warns against carrying such over-the-counter allergy and sinus medication as Sudafed and Vicks inhalers. To get permission to import other allergy medications, narcotics, syringes, or more than one asthma inhaler, travelers must fax the Ministry of Health. Exceptions will not be made at the airport, and Japanese authorities have been known to detain travelers for days while the wheels of justice grind.