I don't know for sure, but it's likely that "Jim" is James Baker, at the time FBI General Counsel and Page's boss. The others may be lawyers at the FBI.
In December, Baker was "reassigned" at the FBI. It's widely suspected that he leaked the dossier to Mother Jones in October 2016.
Trisha Anderson, Charles Newman - Weddings - The New York Times
www.nytimes.com/2011/10/09/.../trisha-anderson-charles-newman-weddings.html
Oct 8, 2011 - The bride, a former clerk for a Supreme Court justice, is a senior counsel to the United States deputy attorney general, in Washington; the bridegroom is a deputy legal adviser to the National Security Council, at the White House.
The bride, 35, who will keep her name, is a senior counsel to James M. Cole, the deputy attorney general, in Washington. Until July she was a clerk for Supreme Court Justice Elena Kagan. She graduated from Yale and received a law degree from Harvard.
The bridegroom, 33, is a deputy legal adviser to the National Security Council, at the White House. He graduated from Duke and received a law degree from the University of Virginia.
Mike might be Horowitz.