I found the best thing for Disney etc, was to put a sticker on the kids back with a telephone number. It doesn't say their name, just a number to contact you on. I also noticed people had written a mobile number on their kids arms in permanent marker. Again a good way to help if a child gets lost.

A companion card is for anyone who has a permanent, life long disability. It is for people that will always need assistance out in the community. It is not so easy to get for young children. It basically means that if you access places that incurs a cost (like public transport, zoo's movies etc) the carer who is assisting the person with a disability can get in for free.

it is companioncard dot org dot au (I think!!)