I actually could've used something like this in a project. Something where I could create a layout "b". On layout "a", place a "layout view" that points to "b". In Activity_Create(), When I do Activity,LoadLayout("a"), it would automatically load layout "b" within the layout view of "a".
I ended up just putting panels on "a" where I wanted "b" loaded and load it during Activity_Create(). Something like the example attached.