[dclowd9901]

This is something you have to decide organizationally. For our part as a frontend team, we've decided when we implement a new feature, it won't be in our old framework. Ever. We've built a way to integrate React into our old world areas of our code. Furthermore, the portion of the old world code that this new React code interacts with will also be converted into React. This way, our code has a sort of 100%+1% movement toward the new framework.

The point is, you need to figure this out as a group and then just implement it as a rule. It can't happen during the code review.