Boot snapper snapshot from another partition

Hi all! This is my situation: i’ve an hard disk with many s.o. installed to try other systems, but i usually use Tumbleweed and Leap 15.1. I would like to restore a Leap 15.1 snapshot from boot menù, but i can only see the Tumbleweed snapshots because i installed Tumbleweed first in time. How can i boot Leap from a its snapshot?

I solved the problem on my own: i mounted the EFI partition on /mnt and i modified grub.cfg file so it launch the Leap grub2 file at boot and i can see the snapshots. I’ve another problem now, but i’m going to open a new thread for this ;).