Page numbering spreads rather than pages

Hi.

I am looking to have automatically updating spread numbers. My reasoning is so that I can decide wether to export the document as a a4 booklet, or as a3 spreads, without having to place it into a additional non-facing a3 document with seperate page numbers set up there.

I found an option using the numbering and lists panel. This however requires me to cmd+shift click each one for it to update. Additionally, this doesn't work as a solution, as I have my page numbers set up on one master, on which 10 other masters are based. When cmd+shift clicking in the main pages, it does not update, but when clicking in the master pages, it does.

I hope this is clear, if not let me know.

Thanks for any help.