First of all, I don't fully understand
what your form does. Maybe you can elaborate a bit on this. For example,
you are writing that there's some LotusScript code that runs after
QuerySave, and that you want that code to return False to QuerySave. I
don't see how that would be possible at all.
It's certainly a good idea to catch
Error 4412, which is raised when a NotesUIDocument.Save() or NotesUIDocument.Refresh()
fails due to a field validation error. Another suggestion is to never use
NotesDocument.Save() -- i.e., the back-end Save operation -- when
saving the document from LotusScript code that runs in the context of a
form or subform, since that would bypass any validation.