The save areas you create are essentially the placeholders where save thumbnails / data is displayed / selected.
The object areas & stuff you define have nothing to do with the save slots themselves, they are purely aesthetical. This is why in the old
(I've not sorted out a new template yet) advanced menu template, I recommend making fail safe queries to prevent users from saving, overwriting & deleting incorrect slots. In my template I had it re-run the same query each time I clicked a slot which determined which save options should be enabled.https://www.dropbox.com/sh/wgfa956ohxcfwya/AABLfqZ0uWIieMaNB...
It's from a couple years ago, but it should be still ok for a quick reference.