Movies such as Back to the Future and Terminator throw around a theory of time travel that if you went to the past and did something in the past, it would cause a different time stream to be created. I feel this is a flawed theory. How does that person end up in the alternate time line and how does the change affect the new timeline? Well it doesn't. I've used this theory for my OC Kitty Hawk and that her just being in the past causes the chain of events leading to her birth. The way I see time travel is that when someone goes back in time, the things they do lead to them traveling back in time.
This is what MLP showed in the episode "It's About Time". Twilight went back in time to stop herself from worrying about an appoccalypse that she created after seeing her future self, beaten up and battered. She causes the chain of events leading to her time travel, because if she had no reason to travel back in time or wasn't able to travel back in time then those events wouldn't ever happen.
It's like someone going back to kill someone who lives in the present. If they succeed in their mission then they won't have a reason to go back in time in the present and then a paradox goes on because now you're not in the past. And the timeline shifts again so this whole point in time has been wonked out going between either timeline where you went back and where you didn't.
Now that I think about it a little more, you do create an alternate timeline. Are you guys as confused as I am now xD