I just got a new Windows 10 computer (dell Inspiron) and am looking to start dual-booting, but I want to be sure I don't destroy the bootable sector of my PC. The Inspiron BIOS has a UEFI boot selector which currently displays "Windows Boot Manager" and $nameofmybootableusb. They both boot fine, but when I install Linux (Mint) I want to be able to select either GRUB or Windows Boot Manager from this window, where WBM boots to Windows and Grub boots to Mint. I realize that this is likely a complicated request, so thank you in advance for any help you can offer! Picture of the BIOS screen, if that's helpful
Make an external boot media (USB or Optical) and put a GRUB loader on that. Configure to allow booting the fixed disk partition of interest. Assuming your boot drive order works to allow that, use that media as a key to boot your alternate system.
I modified a Ubuntu boot image to allow that sort of thing