My suggestion: To have a "How to lock your groups!" banner at the top or bottom of the Trade Settings/Trading Center so that people see it, and can click it and follow it to the tutorial. It doesn't even have to be a banner! Perhaps it could simply be large, bolded text, so that people can see and learn how to lock their pet groups.
It would help a lot of people, and hopefully reduce confusion and frustration with people who don't lock their groups, but still don't want to trade their pets. (We all know people ignore Trading Rules or Group/Pet Names!
![Laughing :lol:](./images/smilies/icon_lol.gif)