Prevent creation of duplicate subtasks

[Fariz Aliverdiyev]

Hello!

Is there a way to not create duplicate subtasks if they were created before?

For example, parent issue uses workflow Open - In Progress - Done,  and on "In Progress" status 3 subtasks are created automatically. How to avoid subtask creating when parent issue is reopened, moved to "In Progress" status and change status of subtasks which were created before to initial one?

Thank you in advance. 

[Aron Gombas _Midori_]

I think your automation should check if the parent issue has sub-task.

If not, create the 3. If yes, don't do anything.

[Fariz Aliverdiyev]

Thank you for answer, but how can I write "don't do anything" in Automation rule?