GitHub currently allows you to change the base branch of a pull request, which would allow you chain pull requests together so that the unique diff can be seen. The issue with this is that it only works with upstream branches.

I would like to have the ability to mark a Pull Request as a Child of another pull request. In this case the child PR would not be able to be merged until the parent is merged or the marking is changed. Also, the diff would only show the differences in regards to the parent PR.

These features are not possible when continuously working on a feature or set of features that depend on each other and require review merging one piece at a time a branch or number of branches ON A FORKED BRANCH. This often leaves me having to manually manage a chain of branches on a local repo, getting feedback on one piece at a time without a reviewer being able to see the upcoming changes as well.