Could you please let us know why the technical writers are supposed to do check-ins on a developer/feature branch?
This sounds to me like a very risky situation in the first place.
I am not familiar with Git though, but would it be possible to set up a folder/repository for the writers where they can write independent from the developer/feature branches? And maybe the developer branches need to make references to this folder/repository to avoid these conflicts? I've found something about using Git submodules in such a case: https://stackoverflow.com/questions/36554810/how-to-link-folder-from-a-git-repo-to-another-repo
In Subversion, our tech writers have their own folder, but they work in same repository as the developers. So we can at least use svn:externals.
Hope this helps somehow,