@rockedge Thanks for the quick reply.
As far as I understand, adrv_xxx_.sfs is the top layer, which is only overwritten by changes in the savefile.
So that e.g. changes in /root/concyrc can be made persistent (conkyrc is in adrv_xxx_.sfs) adrv_xxx_.sfs must be merged into e.g. ydrv or bdrv or a remastering must take place so that the content of the save file is then copied into adrv is at the top and in adrv there is only the content of the save file (not mixed with the original adrv).
That's no problem, I do it that way too. A possible downside to doing this is that the original structure of puppy is modified, which sometimes makes debugging difficult.