FB.ui Request dialogs: (With method: ‘apprequests’) allow you to send a request from your app.
http://developers.facebook.com/docs/reference/dialogs/requests/
This says, you can specify one friend in the two value. However I want to specify N friends which are preselected, but can be edited. Is it possible in this widget. If not, What alternate widgets can I use
This isn’t possible via that Facebook javascript sdk, most likely to be less spammy and not default to sending to every single person a user is friends with. The way to get around this would be to build your own dialog using the graph api. You would retrieve all the users that a person is friends with, present them with your own dialog to let them choose users, and then send graph api requests over for each request.
Update:
Per Facebook’s blog post, you can only send invitations to users through their Requests dialog. And this dialog will not let you pre-populate all users as checked. Graph api can only send to other users that have authenticated with the app.