Hi Marco.
You can save macro page separately as xml file.
This can make it even more confusing. If you make changes to macro page of particular preset afterwards, you get a warning message saying the macro page has changed, do you want to keep current or reload from file.
But if you are careful and organised, doing it this way should let you make changes to a saved macro page. Then when you rebuild the library all presets using the macro page should pick up the changes.