Q: How to add default message in facebook send dialog message box on friends invite I need to send message to my facebooks friends which should include:
- default text message
- url
- my custom message
and I need to know to whom this message was sent.
Please advise how this can be done

A: Have a look at https://developers.facebook.com/docs/sharing/reference/send-dialog
This states that 

Facebook messages are a channel for person-to-person communication, and not for apps to send messages, or encourage people to spam their friends. In general, games on Facebook.com should use requests when communicating in game status (its your turn), inviting people to use an application, or sending messages to multiple people. You should offer the Send Dialog in situations when someone might otherwise send an email.

So I doubt that what you want to do adheres to Facebook's policies, and therefore will likely trigger a deactivation of your app.
