Thanks for this - I'll fiddle with it and see if it's clearer - I'm sure I'm not the only one to find this confusing, so I'll reply with results but here are also a few points which are still vague to me - any thoughts welcome, but i'll revise when i repost
"add new instance" appeared to only open a new, empty VEP mixer, which I would then configure from scratch, and preserve from with the DAW (using Pro Tools and Logic). It doesn't appear to offer a choice of existing instances, and I haven't tried typing in the name of a preserved instance, but is that what you do to add one that you've saved? (and delete instance - does it only remove it from the metaframe or delete it entirely?)
in case it's helpful to others or to anyone with helpful suggestions - here's my workflow:
what i am trying to do is establish a recurring set of instruments, say orchestra and rhythm section, as a template metaframe on the slave.
as i come to new music where i need special instruments, add those, while still having access to my basic set. and ideally save THAT as it's own metaframe, so i can revert to the basic set when necessary.
i've saved the basics as BASIC - metaframe, and in the DAW, have a template session with those instances connected, (decoupled - as I understand this is the way to leave the metaframe loaded in VEP, so i can open other master sessions without reloading all my instruments).
when i need new instruments, i add a new VEP instance in the DAW, and configure that new instance in VEP, and save that set of 3 instances as a new metaframe. when trying to access instances preserved before i discovered that order, that's when i have problems.
I did what the first reply suggested, and opening the saved Project would open unpredictable things- it would open the old instance with the name of one of the two open instances in the template metaframe, and close one or both of those