https://www.youtube.com/playlist?list=PLlinEHqn6JHU_Zdc2Py_iuUTiyxQ1M2WE
Use the search panel to find the task you want to merge.
Click the Merge icon in the Maintain Column.
Merge two primary tasks together, for example, if more than one person reported a broken elevator. When you merge tasks, the basic information of destination task will remain, however you won't see basic information associated with any merged tasks. All sub-tasks, attachments and notes of the merged task(s) are moved to the destination task.
Click the icon to choose one or more tasks to merge into that task (the destination task).
On the Merge Task screen, use the Search Panel to find the task(s) you want to merge into the primary task. Select the checkbox(es) then click Merge to merge the task(s) into the original task. If a member entered a task that was merged, they'll receive a notification that their task has been merged with another task.