Originally Posted by
Iscah
G'raha didn't "jump timelines" but travelled back in time along a single timeline. It was his actions upon reaching that earlier point in the timeline that created a split, resulting in the path we are currently on. (Though due to the oddities of time logic, that means they have always existed in parallel, even "before" he travelled back.)
As far as we know, the Crystal Tower time machine has not been shown to be able to jump from one timeline to another.
It's not impossible for someone with a more advanced space-time machine to find their way across multiple threads of timelines, but I don't really want the story to go there.
I also would prefer that they keep multiple timelines to a minimum, only created in exceptional circumstances, not created spontaneously every time someone rolls a dice. "Only when a time traveller breaks something" seems like a straightforward rule for the sanity of the narrative.