I will end my part in this silliness by referring you to the question posed by the original poster, to wit, "what is the best way to clue EMT's to medical facts?" Note they didn't ask what are some methods that other people use.

The best way, as requested by the original poster is the way that myself and others who actually work in the emergency medical services is the use of the Medical Alert system.

Any other method is less effective.

Jakam, when you find your vetted source, they will agree with the above statement.

I sincerely hope that you and your family never have occasion to need a medical alert system of any kind.