Hollywoodland

My dad and I stayed up til 4 in the morning yesterday arguing over how in Back to the Future II when Old Biff from 2015 goes back to 1955 to give his younger self the Sports Almanac, how was he able to return to his 2015 reality to put the DeLorean back where he found it, when the 2015 that Old Biff returned to should have been the new 2015 he created in which he is now a wealthy tyrant married to Lorraine and controlling all of Hill Valley. The 2015 Old Biff came from should have started fading away like the photograph of Marty and his siblings in the first movie.

We argued over this for 2 hours.