we were NOT crazy !!
see attached files, the sequence works. (see dropbox link, the upload link is not working for me)
https://www.dropbox.com/sh/obidht1abfjmcl2/AAAGzohgwKZDG328o0iPo6woa?dl=0 first, see the settings fur quick-save.
then, as noted above, the CAPTURE -> View and EDIT settings, for "DO NOT CHANGE CURRENT IMAGE".
i then had file name in QUICK CAPTURE as "ORIGINAL-101.jpg", etc.
first two captures incremented these numbers.
THEN, on the fly, at "ORIGINAL-109", I changed the SAVE AS, (in hte SAVE AS BOX, NOT in the QUICK-SAVE), to NEW-109.jpg.
that file got saved as NEW-109;jpg, and the NEXT file SAVE AS request shows "NEW-111.jpg", and it saved it successfully.
now, all these images looked the same because i used hte blank scanner, but I will VERIFY by now changing actual scan source images, to make sure that i'm getting unique files, but I KNEW that somehow that name was changable on the fly (either by bug or by design)
If it IS by bug, then please don't FIX the bug, because the bug does not seem to have ever affected any one; and maybe make it included as a FEATURE, because, as in past posts, this is a desirable item !
thanks
nick