Once the changes have been accepted, possibly after a few revisions of the branch, it can be merged by one of the relax developers back into the primary relax repository. Taking the MOLMOL macro example again, assuming seven revisions of that branch, the relax developer will add your remote git repository as a remote and pull in the branch. Then it will be rebased and merged to master with
$ git checkout molmol_macros/r7
$ git rebase -i master
$ git checkout master
$ git merge molmol_macros/r7
This ensures a clean and linear history for the master branch. If the rebase process results in conflicts that the relax developer cannot fix, you will be asked to create a new molmol_macros/r8 branch and perform the rebase and conflict resolution yourself.
Note that web interface `pull requests' or `merge requests' will not be used, and that it is better to send an email to the relax developer mailing list rather than to use these features of the web interface (which may be missed by the relax developers, especially when a relax mirror is used).
The relax user manual (PDF), created 2019-03-08.