Hey there, Tef.
As far as I am concerned, this is not an available feature in a standard workflow in JIRA that is integrated with GreenHopper. I believe that you might want to develop your own plugin to achieve this. You can also try to consult the Atlassian Experts to seek their advice whether this is somehow achievable or not.
As for the plugin development, you can try to check on the following community chat room for development questions. This might be able to shed some light on this requirement
Hope it helps!
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