# IN UEFI BIOS, change bootloader to Debian drive so it will boot debian.
su – root
vi /etc/default/grub
# UNCOMMENT this line as such.
GRUB_DISABLE_OS_PROBER="false"

# FIND DRIVE UUID THAT HAS WINDOWS "ntfs"

blkid

/dev/mapper/deb1--vg-swap_1: UUID="b7c4c5a4-40bd-4a4a-bfaa-226abf07df2e" TYPE="swap"
/dev/sdb2: BLOCK_SIZE="512" UUID="58F8B0AFF8B08CAE" TYPE="ntfs" PARTUUID="07d5ec7a-02"
/dev/sdb3: BLOCK_SIZE="512" UUID="A4EA4330EA42FDD4" TYPE="ntfs" PARTUUID="07d5ec7a-03"
/dev/sdb1: LABEL="System Reserved" BLOCK_SIZE="512" UUID="76D4AFBCD4AF7CCD" TYPE="ntfs" PARTUUID="07d5ec7a-01"
/dev/mapper/deb1--vg-root: UUID="ac1e1092-e501-49bc-b839-67006ef89234" BLOCK_SIZE="4096" TYPE="ext4"
/dev/sda5: UUID="9xmigV-MtN3-tC0m-FjuC-He9P-MEGg-Fr4KLd" TYPE="LVM2_member" PARTUUID="928bac7e-05"
/dev/sda1: UUID="49a1c3fa-1bd5-489d-82d9-b2c6ce6f45e2" BLOCK_SIZE="1024" TYPE="ext2" PARTUUID="928bac7e-01"

sudo apt install grub-customizer

# EXAMPLE 1 - ADDING WINDOWS TO GRUB  ENTRY
Name: Windows 10 Pro Boot Manager (on /dev/sdb1)
Type: Other

insmod part_msdos
insmod ntfs
set root='hd0,msdos1'
if [ x$feature_platform_search_hint = xy ]; then
  search --no-floppy --fs-uuid --set=root --hint-bios=hd0,msdos1 --hint-efi=hd0,msdos1 --hint-baremetal=ahci0,msdos1  76D4AFBCD4AF7CCD
else
  search --no-floppy --fs-uuid --set=root 76D4AFBCD4AF7CCD
fi
parttool ${root} hidden-
drivemap -s (hd0) ${root}
chainloader +1

# EXAMPLE 2
Name: Windows 10 Pro Boot Manager (on /dev/nvme0n1p1)
Type: Other

insmod part_gpt
insmod fat
search --no-floppy --fs-uuid --set=root BAE6-96B7
chainloader /EFI/Microsoft/Boot/bootmgfw.efi

# EXAMPLE 3
Name: Windows 10 Pro Boot Manager (on /dev/nvme0n1p1)
Type: Other

insmod part_gpt
insmod fat
search --no-floppy --fs-uuid --set=root EFC8-2865
chainloader /EFI/Microsoft/Boot/bootmgfw.efi