[ It mattered to her! She hasn't spent her whole life fixing and tending to Destiny Books just to toss it away, even if the destiny belonged to a stranger she'd never met. ]

I don't know the difference, only that we are not supposed to interfere in the affairs of mortals. Shifu never talked about mortals that live beyond the Three Realms before. What if we do destroy their primordial spirit?

What if the rift isn't enough to prevent that?