I have my custom USB device with grub 2.02 and syslinux as bootloaders. Now I wonder If there is any chance to also have the bootable Windows 7 and Windows 10 installers on the same device (as grub or syslinux menu items).
My question is: Is it possible to do it without any all-in-one builders like WinSetupFromUSB or YUMI, just with grub or syslinux and maybe some other low level tools. If yes, how it is done technically? I don't need a detailed guide, just the big picture.
I know I can boot Windows bootmgr from grub or syslinux, but what next? How to have both Windows installers on the same partition?