I have disks sda and sdb. The disk sda contains OpenSUSE Tumbleweed. I want to install OpenSUSE LEAP 15 on the disk sdb. When I run installer, it shows me a plan of partitioning which looks fine except one line: mount of sda1 to /boot/efi. So, it wants to mount the partition from the sda where is OpenSUSE Tumbleweed while I want to install all to sdb. I suppose it will lead to common boot menu with selection from both OpenSUSEs: from sda and sdb. Or I'm wrong? Is it safe? I tried to change this line with menu but no way: it always finds sda1 and add to plan a mounting of it to /boot/efi.
Another way is to detach sda disk at whole and to install new OpenSUSE which I suppose will lead to selection of boot device from "BIOS" motherboard menu.
So, what is the safe way?