Why does GRUB boot Windows 10 instead of Windows 7?

Question

linux

Hello.
Installed a zoo of operating systems on the PC: Windows 7, Windows 10, Debian 7 (without GRUB), Debian 8 (with GRUB).
After that, when booting, GRUB allowed you to choose between Debian 7 and Debian 8 (although during installation it wrote what the Windows bootloader sees).
After executing the "update-grub" command, it became possible to select Debian 7, Debian 8, Windows 7 from the list.
But when choosing Windows 7, Windows 10 is loaded.
The disk is now partitioned into:
1 - NTFS - 100 MB
2 - NTFS - Windows 7
3 - NTFS - Windows 10
4 - ext4 - Debian 7
5 - swap
6 - ext4 - Debian 8
7 - unallocated area
grub.cfg

Windows 7
set root='hd0,msdos1'

Debian 7
set root='hd0,msdos5'

Debian 8
set root='hd0,msdos7'

Answer 1

You need to tweak the Windows bootloader (BCD) by adding a second Windows to its configuration.
Here is one of the relevant instructions for you: www.oszone.net/10998/Edit_Boot_Menu#add