Fixed parent content across multiple page sizes

I have an InDesign document with multiple page sizes and I want the content in my uber parent page to remain in the slug across my other sub-parent pages (of different page sizes). This way I can update the slug on one page and it updates across all parent pages. Only problem is getting it to remain fixed to the bottom of the page (within the slug).

I'm aware of this thread but am not good with scripts. I can import and run them but would need someone to explain how to use it. Possible to do this without a script? If not, would appreciate some scripting support.