Aha, that's a missing piece of the puzzle, thanks. Well, of course they don't want her to be interviewed.
Obama’s mother went to Mercer Island High School
excerpt:
Following it all closely is Susan Blake of Mercer Island, who went to Mercer Island High School with Obama’s mother Stanley Ann Dunham, and graduated with her close friend in 1960.
“The day after we graduated, she (Stanley) and her mother were on an airplane to Hawaii, to join her father who had already found a home for them to live,” says Blake.
Blake recalls keeping in touch by mail. “She said she was in love with an African exchange student from Kenya, and in spring wrote to say she was marrying him, (the senior) Barack Obama. ... One day, after ‘Barry’ was born, she came for an afternoon, (on her way from Hawaii to join her husband at Harvard.)” Blake remembers “the infant. He was sweet and pink and very new.” The two talked and cuddled the baby. “And I changed Barack Obama’s diapers.”
http://www.bizjournals.com/seattle/stories/2008/01/14/tidbits2.html
(The kenyan student left Hawaii on the 22nd of June 1962, met Hal Abercrombie and his wife at ‘The Blue Fox’ on the mainland, and did a bus trip to Cambridge in time to start Harvard in September.)
http://www.washingtonpost.com/wp-dyn/content/article/2008/08/22/AR2008082201679_5.html
...On his way east, Obama stopped in San Francisco and went to dinner at the Blue Fox in the financial district with Hal Abercrombie, who had moved to the city with his wife, Shirley...