Unable to validate if user has viewed all pages

Hi All,

I'm working on a module using Storyline 360, and can't find a way to make sure that the user clicks on all pages (which are different layers in the slide). The problem is that two of these pages have buttons (Previous and Next) which are not on the main layer. As in, I cannot insert the buttons for those on the main layer because they don't serve any function other than to move between those two layers/pages only. I guess that's why I can't reference any variables on those two on the main layer to ensure that the user clicks on both before clicking on Next on the main screen to move to the following slide. Any workarounds for this? I have an alert (message) in place for the rest of the layers if the user tries to move forward without reading the content on those. 

Thanks in advance.