Thread:Project:Support desk/Force transclusion of nested template.

I'm trying to preload text into new articles based on a master template. Each article is to be assigned to one of seven categories. At the top of each category I use an input box from the Extension:InputBox to input the new article title and to preload the template. These are all the lesson plans for the Crew Chief in Training modules. below and click the button.
 * To create a new lesson plan based on the Crew Chief in Training lesson plan template, fill in the Title

This works perfectly if I directly preload the master template, the new article opens in the editor with the code from the master template already entered. But preloading the master template would make them all the same and I need to customize each one with the correct category tag inserted based on the category it's originating from. Preload does not take parameters so I created a custom template for each category that includes the correct category and calls the master template. Do Not Edit this template! This template calls the Master Lesson Plan Template and only exists to include in the correct categories. Any changes for the lesson plan template should be made to the Master.

However when I do this, the master template is not transcluded, instead I get this in the editor:

I have researched Transclusion, Templates, Substitution, Preloading text... until my head is swimming trying to understand it all. => => If I use  when I save the custom template it goes and grabs the master template at that time and saves it to the custom template replacing the. But then if I later make an update to the master template the custom templates will all be out of sync and since the was replaced I can't even just open the custom templates up and resave them, I'd have to cut out the text from the old master and replace it with  in which case I might as well cut and paste in the whole master template text. I'd really like to only have one master to change.

Am I going about this wrong? I thought nesting would go and grab down the whole chain?

PS: The Show Preview button on this editor doesn't appear to do anything.