Automate child rows

I'm trying to set up a task-management sheet on smartsheet. I have a form using conditional logic so that users will enter different kinds of info based on the type of task they are submitting. For example, a program task will bring up different fields than an instrumentation task. I would also like to see if there is a way to automatically populate child rows beneath a task based on the task type. For example I would want the three subtasks of "bridging," "qualification," and "validation" to populate beneath any task that is submitted as a platform task. An instrumentation task would have 3 different subtasks. Is there any way to do this? I'd be open to using third party apps if that's an option.