Ok, i figured it out by myself. But maybe someone else has the same question, this is how i merged the new roles:
I have created a backup of the configuration by using securityadmin.sh, then merged the new roles (by diff’ing the old and new version distribution files) into my backup configuration file and finally uploaded only the modified file to my opensearch instance.
The command options are explained here:
I’ve someone has a better idea for this, i am happy to get a comment.