As for the sub-tasks - any issue placed in "Scheduled Issues" table (also with "inactive" status), can be managed with sub-task linking.
Subtasks in Cloud
To manage subtasks simply click "Add subtasks" button placed next to the name of SI.
A new prompt with all necessary information will be presented:
After clicking any of the two present "Add Subtask" buttons, next screen will load, with a linking option present. On a top of it you must provide a "subtask name", then scroll down and fill-in below presented information, as in the below presented example:
After pressing "Submit" (4↗) new linked sub-task will be created and "No subtasks created" (1↖) information will disappear.
Before pressing "Submit" button, select a reason for linking issue (2↗) i.e. "relates to" and then find one more or more that fits to it.
After submitting recently edited one, "Add Subtask" (3↖) button will become active again, allowing you to create more dedicated subtasks (up to 15 max.), each with unique name, linked issues and fields to fill in.
For more of the features in regards to instant operations on existing sub-tasks in regards to cloning and removing it, please refer to below image:
Any created sub-task can be quickly replicated or removed - when you hover a mouse cursor over any of existing sub-tasks(1↖), two more options are to appear at the same time - clone and delete. Move cursor horizontally to the right (stay on the same line as a sub-task is placed) to choose a desired option.
Subtasks in Server, Data Center
Subtasks management in Server and Data Center is easy. You can add them to any Scheduled Issue in Jira in two ways. Go to Scheduled Issue details page and click on the “+Add” button (1) or Add Sub-Task in More actions (2).
Both operations result in displaying the following prompt on your screen. You can set here all details of Subtask. Remember, that the fields that will be displayed depend on the settings in your Jira project.
Fill all information that are important to you and create a subtask using “Add” (1) button.
In Scheduled Issue details page you should see that Subtask has been created (1). If you want to do some changes you can click on the edit button (2). Then you should see similar prompt as during creation. Confirm changes clicking on “Save” button.
Subtask can be also removed easily using the delete button (4) or trash icon (3).
