"Already used" in User profile edit page. using Japanese
Using Jamroom
Most of the time you don't want to modify any of the jamroom files because those changes will be over-written if there is a module update. Instead what you want to do is use the "Events and Listeners" system to adjust other modules by building your own.
Then you know that since your custom module will never be updated other than by you that your changes will always work.
Docs: "Events and Listeners"
https://www.jamroom.net/the-jamroom-network/documentation/module-developer-guide/1011/events-and-listeners
If its not possible to get to the point you want to adjust without changing a core module let us know and we'll add in an event close to the point you're after or adjust the core module with the change.