how to make mergerfs behave like I did aufs behave: only write everything new or modified (including paths, everything..) to a single writable folder?

I need this behavior because I need to know what the application using the merged folder will do, so I can backup it properly and consistently with small backups. I need to force it behave like I did with aufs because I am migrating my script that used aufs, but not only because of that. That behavior is mandatory for the layers I created and were working very well. All my work branches (directories) are subfolders of the same folder (that is where the merged folder is placed), therefore share the same available space. These options work +- well: defaults,allow_other,use_ino,category.action=ff,category.create=ff,category.search=ff but if I modify one file at the merged folder, it will remove the file from the original folder :O and create/update the modified file on the first folder found :(, it should not touch the original file :(. If there is several overrides, it deletes them all leaving only the last modification on the first folder :O, it is good I know, but not for my script/useCase. If I make all branches' folders and subfolders readonly, this will prevent the deletion of the files, so all updates will go to the first folder. But then, I will still need to make each branch(subfolders and files too) RW, change things there and do not forget to set it RO again or things will mess up. So I still can't make it behave like AUFS did. It is close but not equal. PS.: ubuntu22.04 has aufs no more, so no going back