Starting a hangout with a list of users invited

Question

I have a website where is discussion is happening among some people with valid gmail ids. If one of them in the discussion clicks on the google hangout button, I need to start a

Answer 1

I believe this is new capability since the question was asked, but it is now possible to create a hangout button which starts a hangout with a list of users invited (based upon G+ Profile Id, G+ Circle Id, or Email Address).

See details at https://developers.google.com/+/hangouts/button#invite_parameters.

Note: The list is only a suggestion to the user that starts the Hangout. Before the Hangout begins, that user will be able to skip the invite or change the list of people.