Thank-you for your additional notes. I have to start getting ready to
close up the cottage and relocate to another residence tomorrow where
I will stay until spring, and so I haven't much time to think about a
response.
I think the upajaati metre applies to a stanza or a group of them and
not to one paada alone. The Indavajiraa metre, on the other hand, can
apply to the metre of one paada or stanzas if all the paadas have the
same metre.
One of the purposes of a vyaakara.na grammar is to preserve the
canonical language. For Pali, I think it may have come too late too
little to save the early language of the Tipitaka.