the page on the right side is always just the page you're on
and the page on the left side is always whatever footer page you chose
you know
Screenshot 2024-01-20 at 11.19.10.png
in lay options → footers
you can select these boxes where it says:
"Show a select input in the Project Edit Screen to choose a Footer for individual Projects"
then for each project/page/category you can choose a different footer page.
so this way you can have different pages that show on the left side of the splitscreen layout
and whatever page you're on will always be on the right side
there are no other settings for this, so im not sure if that covers your use case