Per your request from the below quoted text,
elaborating on this step: Use more than one EFI partition. A drive can
have more than one EFI partition. Additional EFI partitions do not
have to reside at the beginning of the drive.
here is some info (I will make edits shortly when I have more time):
An EFI partition (sometimes referred to as an ESP ...
I think I may be able to help you triple boot, although I haven't tried triple booting yet. I do know how to install Windows on a separate SSD, and I'm pretty sure you can just install Linux by partitioning the SSD. Here are the steps:
Step 1: First, you have to install both Windows 10 and Ubuntu ISO files. Ubuntu from here: Ubuntu ISO File, and Windows 10 ...
I was able to change the default boot volume which is just a partial resolution of my question. This is done by using an alternate form of the bless command based on an un-mounted storage device. From the intended default volume OS booted:
$ sudo bless --device /dev/disk1s1 --setBoot
(where disk1s1 is the current and intended volume which can be observed ...