Random list. (Custom Invit.php)

Hello,

I think it might interest a lot of users.

I edit the invit.php files for groups, pages, and events to present the member's friends as a list.
I have limited this list to 100 items.
I would like to get a random list so that I never have the same items.
How can I do ?
Where is the list generated?

Also, with what I did, when we check the box of the member to initer (see the screen copy) must choose from a list, how to avoid this step after you??

Best regards.

Eric