It seems to work very well for Husbands and Wives. For instance my daughter is separated from her Husband. I used the _SEP function and her Husband is now listed as Ex-Husband. So far so good.
But, she had a previous relationship (not married). I used the _NMR function to successfully change her first Partner from Husband to Partner. But when I then use the _SEP function on that relationship it still lists him as Partner and not as Ex-Partner. In the Family Group information they are listed as Separated ok, but he is still listed as Partner.
Are we pretty much stuck with that or can we further configure it?
No, that is all there is to it. There is no “ex-partner” terminology. I’m not actually sure if ex-husband should be there for separated spouses. Isn’t there an argument that such a change should be restricted to an official process such as divorce? Legally your daughter is still married, and still has a “husband”.