Griff chased Marty and Doc on the streets of Hill Valley as they ran they bumped into someone "Hey watch where your going!" Marty junior shouted but then he screamed as he saw it was he father and blacked out. "Quick Marty! We need to get your son to an alleyway before Griff sees us!"
In the back of the alley, Marty then thought "Back in 2015, Dad was still alive why and how is he dead?" "Well Marty, the other you sadly murdered him with a gun in the alley way he was killed! We need to fix this fast before the timeline catches up to 2016!"
"Dad?" Marty junior says "Uh this going to take a lot of explaining to do... ..."