I know about using branches for multiple pull requests, that\'s fine.
But what about this scenario:
It is a communication problem, more than a Git issue.
I prefer making separate PR, as their intent and scope differs.
But, in the PR message, one must clearly states if that PR is suppose to supersede another PR.
That way, the original repo project manager can try those different PR separately, gauging their effects, and select the appropriate one.
He can then ask initial contributors to redo their PR (on their same branch) based on the work of the PR he or she finally selected.