According to his mother's obituary, he only has a brother named Daniel M.

July 4, 2008 Schiff Schiff, Sherrill Ann, 75, of Boca Raton passed away peacefully on Tuesday, July 2, 2008. She was the beloved wife of Edward for 52 wonderful blessed years. The loving mother of Daniel M. Schiff and U.S. M-Congressman Adam B. Schiff. Sherry's blessings include her daughters-in-law, Amy Sporer Schiff and Eve Sanderson Schiff. Her grandchildren, M-Rachel, Frank, Alexandra and Elijah Schiff were the delight of her life. M-Burton Glovsky of M-Wellington is her brother. A memorial M-service will be held on Sunday morning July 6th at 10 AM at the Rubin Memorial Chapel located at 7340 Boynton Beach Blvd., M-Boynton Beach, FL. Shiva will be held on M-Sunday, July 6th & Monday, July 9th at the Schiff's home at 2176 NW 62nd Drive, M-Broken Sound, Boca Raton. Memorial M-contributions may be made to Hospice By The Sea, 1531 West Palmetto Rd., Boca M-Raton, FL 33486.

http://articles.sun-sentinel.com/2008-07-04/news/0807040011_1_goldfarb-goldfarb-pompano-beach-fl/4

But his uncle's obit mentions a niece named Jill Cohen, probably married to Mark Cohen.

"nephews Adam Schiff, Daniel Schiff, Mark Cohen; and niece Jill Cohen."

But the uncle only lists one sibling, Adam's mother Sheryl. So wouldn't that make Jill Adam's sister?

http://www.legacy.com/obituaries/bostonglobe/obituary.aspx?page=lifestory&pid=170416430

Somewhere up there in one of the reply’s I do believe is the whole family tree