Re: Can't boot openSUSE 42.2 from boot menu created by Fedora 24
Check in grub.cfg that the "root=" parameter (plus any "helper" parameters beginning with "rd.") on the SuSe kernel line is pointing to your SuSE root partition.
I usually install new releases of Fedora in fresh partitions to leave me with a working previous version. The install finds my previous kernels but sets them up in Grub pointing to my new root partition so I have to set them back to the correct partitions manually.