You can now assign a parent issue to multiple issues when using batch update in Backlog.
Note: Using parent and child issues (i.e. subtasking) is available for paid plans only; it is not available in the Free plan.
If you need a refresher on batch updating issues, see How to batch update multiple issues.
After selecting the issues to be updated as a batch, click on Edit selected issues.
At the Batch update popup, at the Parent issue field, you can enter the issue key or click Browse to open up a dialog. Enter keywords to search for the issue (that will become the parent issue), and then click on it. Finally, click Submit.
A green alert will show Completed updating. Click on the Back arrow symbol to go to the Issues list page, and you can see that the parent and child issues have been updated.
This update makes it easier to batch update issues and group them under an existing issue at the same time.
Give this new feature a try, and let us know your thoughts and feedback!