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In order to edit a Template, navigate to your project sidebar → Apps → Smart Templates → click on 
3-dots menu for the Template you want to edit
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In order to add an Issue to your Template, navigate to the parent Issue → 3-dots menu → select the Add child Issue option
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Navigate to the Issue you want to delete → 3-dots menu → click on Delete
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Navigate to the Issue you want to duplicate → 3-dots menu → click on Duplicate
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