Susan Blake’s story is a mess.
It is not unreasonable for people's recollections to have a few inconsistencies. An atheist I once argued with pointed out that the events described in Mathew, Mark, Luke and John don't quite jive with each other. He is correct. They don't. (I argued that since none of the apostles were present at the crucifixion, they got their information second hand from someone who was there. Had they been collaborating, there would be no inconsistencies between their accounts at all.)
The point is, inconsistencies are not unusual in people's recollection of events. In this case, there exists other information which reinforces what Susan Blake said. There is the University of Washington Records showing Ann Obama registered for school there. There is the Polk Directory showing her present there. There is the eyewitness accounts of Maxine Box and Mary Toutonghi. Suffice it to say, that enough evidence exists to require the burden of proof to be placed on any challenger to this account.
I have seen no credible challenge to the notion that Ann Obama/Dunham was in Seattle from August of 1961 through the summer of 1962.