Feature Request: Redlining Prints in Eeschema and PCBnew

By ‘redlining’, do you mean something like this?

Maybe I don’t fully understand your problem but, can you not put your amendments on one of the user layers? (Drawings/Comments or ECO1 or 2 (Engineering Change Order).

for output, it would be fairly easy to plot a combination of any layers you choose together using Python - there are several scripts out there which can do that.

Here is a good start. It will need a minor bit of modification