I've submitted a PR from my fork to the main project on github. It is simply a text file (a specification). It has received many comments, including ones saying that it ought to be two separate documents.
Is there any way I can split it into two parts (the top half and the bottom half) such that both halves keep their comments?
What you can do is to simply fix all change requests in this single file, then do two things:
commit changes with a message like "Fixup: address comments". Note that this could be multiple commits if your change requests are logically organized into different ideas. For example, formatting WORKING code with a formatter is different from fixing a bug detected in code well formatted. In this case it's useful for your reviewers to split the fixup commits into unit changes as you amend your code.
split the edited file into two files and commit the changes with a message like "Fixup: split File into File1 and File2"
Then, if the reviewers are happy with the changes, you can squash everything into a single commit that contains both files, or reset the history and add one commit per each file.
