Thank you so much for your reply.
Like the link method that you told me
If I proceed with batocera-save-overlay
The following error message is displayed and does not apply.
rsync: write failed on "/overlay/saved/usr/lib/libretro/mame2015_libretro.so": No space left on device (28)
rsync error: error in file IO (code 11) at receiver.c (374) [receiver = 3.1.3]
Can't I solve the problem? Please help. Thank you.