Yes you can. Just try to change the Boarding Point before Charting.
If the train is diverted via a nearby route then BP Change is not required also.
Few days back I was supposed to board 12664 from VSKP but as the train bypassed VSKP and it was given stoppages at Duvvada and Simhachalam North, I boarded from Duvvada. Many boarded from Simhachalam North as well.