If my flaky memory serves, an earlier version of Save2SFS had a check box by which, when creating either an adrv or a ydrv, the contents of the other could be excluded. This worked well with my routine: 1st create a ydrv that would rarely change; then create a adrv which could be modified as needed. The current GUI doesn't offer that option.

- Save2SFS Options.png (25.79 KiB) Viewed 4614 times
The "and" in the option "Exclude existing adrv and ydrv" I read to mean both: no choice to exclude one but not the other.
I'm not sure how to retain my routine, except to rename the ydrv (e.g. 0ydrv --anything which will be ignored on boot-up), reboot and then create a new/modified adrv, then rename 0ydrv to ydrv again and reboot.
Perhaps this is where your new SaveToAdrv comes in, viewtopic.php?p=87387#p87387. That post suggests that it only affects Adrv (perhaps unless the "Create new adrv in /tmp" is chosen?). But have I interpreted the post correctly? Using either of the first two options of SaveToAdrv will the contents of a ydrv be excluded from the newly created adrv?
At any rate, how would you suggest creating/modifying adrv so that its contents will not include things already included in a ydrv?