In my opinion, and as mentioned prior by some of the users, this situation is handled differently case-by-case. There are only certain situations when documents from previous product can be grandfathered into a new product, if and only if, the product is closely similar to the predicate. As an example, device A and device B, device B is the second version of device A, and they simply build upon the foundation of device A, the company can reuse the original documents since device B conducts the same actions but adds some more uses. However, as defined by the FDA, if the medical device is drastically different from the predicate, that would mean that the new device would be a brand new medical device and require new written documentation and testing etc. There are moments when grandfathering documentation from an old device and a new one can be problematic when companies uses resources to edit and revised old documentation. Sometimes for new product development, it is sometimes better to not grandfather in documentation.