Leonard Hassen

Corrected entry: When Marty saved his father from being run over by his grandfather, he had automatically altered the future. Shouldn't he and his siblings have disappeared altogether?

Leonard Hassen

Correction: The timestream, as portrayed in the films, is quite resiliant and resistant to change, which is why Marty doesn't vanish immediately. As time passes in the new configuration, that resilience is overcome and things begin to disappear from the timeline, beginning with his older siblings (who are closer to the point of disruption) and ending with Marty himself. Fortunately Marty is able to get the timeline back onto a course that includes him and his siblings before that happens completely.

Tailkinker