Chainloading hands the boot over to Windows (from grub) but windows just thinks its a fresh boot. When windows does EFI changes its only to its own designated partition.
You can even run windows update and when it prompts for reboot to install, you can launch Linux and do whatever, then boot back to windows and the install will continue like you didn’t interrupt it.
The reason two drives works is same as what I mentioned, you have two EFI partitions that are separate.
The only way you will wreck it is if you go into windows device manager and delete the unknown partitions.
I have run a dualboot for 8 years this way.
Chainloading hands the boot over to Windows (from grub) but windows just thinks its a fresh boot. When windows does EFI changes its only to its own designated partition.
You can even run windows update and when it prompts for reboot to install, you can launch Linux and do whatever, then boot back to windows and the install will continue like you didn’t interrupt it.
The reason two drives works is same as what I mentioned, you have two EFI partitions that are separate.
The only way you will wreck it is if you go into windows device manager and delete the unknown partitions.