Both NTLDR and Windows Boot Manager are capable of redirecting to subsequent bootloaders, this feature is intended for dual booting with older versions of Windo

Both NTLDR and Windows Boot Manager are capable of redirecting to subsequent bootloaders, this feature is intended for dual booting with older versions of Windows but can also be used to dual boot into Linux and other operating systems. As an example, if you install Windows 98, then Windows XP, then Windows 10 side by side, the following things happen: 1. Windows 98 installs its bootloader. 2. Windows XP takes a dump of 98's bootloader into a file and then overwrites the MBR with NTLDR. NTLDR is then configured with an option to chainload into 98's bootloader by reading its dump file. 3. Windows 10 takes a dump of NTLDR into a file and then overwrites the MBR with Windows Boot Manager. Windows Boot Manager is then configured with an option to chainload into NTLDR by reading its dump file. This means you can install Windows 10 (and Windows Boot Manager), install Linux and have it install its bootloader (eg: GRUB) somewhere, then configure Windows Boot Manager to chainload the Linux bootloader (eg: GRUB) by reading from wherever it's stored.