Similar questions have been discussed many times on this forum
It seems you want to copy fields filled in transition screen of one issue into the linked issue. You can write a script in post-funciton to access linked issue and update their fields
Here's some samples for updating custom feilds https://community.atlassian.com/t5/Marketplace-Apps-questions/Basic-method-to-update-a-custom-field-with-Scriptrunner/qaq-p/362875
For updating , system fields you can see the API here
Connect with like-minded Atlassian users at free events near you!Find a group
Connect with like-minded Atlassian users at free events near you!
Unfortunately there are no AUG chapters near you at the moment.Start an AUG
We're bringing product updates and pro tips on teamwork to ten cities around the world.Save your spot