Are these Template tasks where in your example the user is picking the 'Create New User Account' from a list of template tasks? If so - you have a lot of options but the easiest would be to just use a Pipeline and whenever a Task is created, search for the template sub-tasks related to that template task and create the sub-tasks via Pipeline. This way the user just has to pick the parent task and the sub-tasks are automatically generated in short order.
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Chayce Duncan
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