Grub2ub1.97 (Question vis-a-vis Grub 1.97 -- aka "Legacy: Grub

I have two HD’s, one with Grub2 (in the extended partition) and one without Grubn (native Windows boot —sigh).

On the primary (the Grub2 HD), I boot to (one of) openSUSE 13.1, Ubuntu 16.04 LTS and (my new favorite, Leap 42.3).

Back in the day (lol), I could “chainload” boot sequences to the secondary OS’es. With Grub2, I do not know how to do the same, to
avoid re-booting to the base (13.1) and running the grub rebuild.

Is their any easy way to do the equivalent of “chainload” in Grub2, to avoid these steps when Ubuntu or Leap 42.3 kernels are upgraded?

Yes, the command is named “chainloader”. Just create menu entry (you can add it to /boot/grub2/custom.cfg, then it is available immediately without running grub2-mkconfig) with something like

menuentry "Chainloader example" {
  chainloader (hd0,msdos2)+1