If it is acceptable to contract “IS” [becoming ‘S, and therefore S for the grid], it is from that moment on a stand-alone thing which can be used whereever it is appropriate.
If you think it is reasonable to write “ONE IS” as “ONE’S”, you can use it from moment on as the 4-letter ONES without any restrictions.
[the apostrophe isn’t an issue anymore nor is the pronunciation]

We thought thát was basically what you said, which is very different from what I thought before. And I/we agree with that.

Therefore the main issue [ ] here is: Is it acceptable to change “IS” into “S” ?
And “ONE IS” into “ONE S”?
And, moreover, is there a difference between the two, or not?

And there we come to a point that we say NO where you say YES, and vice versa.

Even though Chambers gives us “a shortened form of has and is (eg she’s taken it, he’s not here)”, we still think that “IS”=”’S” as a stand-alone cryptic device doesn’t make sense [because we are convinced there should be something anchored to it to justify it - so therefore converting "ONE IS" into "ONE S" is acceptable, though I didn't like it at all, because the clue could/should have been "Asian one's adopted by another?" instead of "Asian one is adopted by another?"].
And secondly, there is no indication in the clue that we should make a contraction.
Although, I admit, that is not always necessary, certainly here it is, because this is a rather special situation – it is reasonable to ask for that.

Chifonie must have known what he was doing.
And I do wonder whether he did this deliberately (to provoke?), because there are alternatives, aren’t there?

That’s fine. Re your Q to setter, it might have been easier to have a clue something roughly like ‘Is last speaker a follower?’ Certainly a different clue would have saved us all a lot of bother!

And sorry for all this, Chifonie – however, why did you do it this way?
[a rhetorical question, please no answer]

Many thanks again for your patience.
I suspect we are going to go round in ever-decreasing circles till we disappear …. I’m not sure where we are at this point!

1. Sil Your 3 re pronunciation. I am not worried about this in the example. I am simply pointing out that ‘ones’ in Indonesian not only ignores the apostrophe but also utterly transforms the pronunciation. In the context of the answer, the four letters o+n+e+s simply become a meaningless part of the word Indonesian, and we find this omission plus pronunciation change quite acceptable.

Re your 2. ‘It is not relevant whether the apostrophe comes at the start of the clue or not – it’s just about what it means in the context of the clue’
I think I am rather saying that it may legitimately mean nothing in the answer since it is transformed from being a semantic and syntactic element in the context of the clue to being a non semantic or syntactic letter or set of letters in the answer. In the course of this transformation, its syntactic/semantic attachment to the word(s) in the clue is lost. So if ‘is’ is represented by “‘s” in Chifonie’s it seems acceptable to lift it out of there and put it anywhere more or less in the answer with the unprintable ‘ removed.

re your (1) I am not sure what you mean here. I am merely suggesting that the grammatical rules attaching to apostrophised letters in a clue do not necessarily matter for the answer – so long as this does not badly obscure the answer. In this case it is pretty obvious that stalker is the answer – I believe you must have seen it quickly and found you did not like it. I myself am more neutral than hostile towards it.

2. As I pointed out the apostrophe is a mess now and pretty well always has been. Clear though not wholly consistent rules were invented by printers in the early C19 and became dominant for a time esp. C19 and C20 but are quickly going (no doubt regrettably for many including me) by the board. For this reason I am perhaps less worried about ignoring the small print of these rules in the answer to a clue.

Many thanks once again for taking so much trouble.

Coming back to tupu’s post (# 51), I read three things from it which I try to summarise [tell me if I'm wrong]:

(1)
When a part of a clue must be ‘shortened’ using an apostrophe, one shouldn’t use the letter(s) attached to the apostrophe in an answer, because the apostrophe is in fact part of the clue as well [but cannot be written in the answer]
(2)
It is not relevant whether the apostrophe comes at the start of the clue or not – it’s just about what it means in the context of the clue
(3)
When we use word A as a part of / in combination with word B, the A part of the answer A/B should [preferably?] have the same pronunciation as the original word A

My view:

re (1):
I can see where you coming from, but that leaves me with things like:
- LL for “will shortly”, is that acceptable?
- IM for “setter’s” or a similar thing, acceptable?
- “Asian one’s adopted by another”, alright or not?
All three, things that we see quite often in Crosswordland.

re (2):
From your point of view, that is reasonable.
But as no-one ever says “‘s speaker” mmeaning “is stalker” [when there's nothing in front of "is"], it is at least very ugly here.
And when Chambers tells us “a shortened form of has and is (eg she’s taken it, he’s not here)”, it surely means that it is not a ‘S on its own.

re (3):
Well, I do in a way agree about this, but it’s apparently not how it works in Crosswordland.
When I came to this site two years ago as a novice, I questioned a situation in which a homophone of A was used together with B in A/B, while the A part of the properly pronounced whole A/B sounded different from A’s homophone.
This was immediately dismissed as a kind of nonsense.
Solving last week’s Pasquale I had to think of that again, when the CONNE[d] part of CLOISONNÉ (with accent aigu) didn’t sound like that in the final answer. But as I know better (?) nowadays, I went on and forgot about it [until today ].

I appreciate the deepness of our current discussion, but playing with punctuation marks, apostrophes etc is part of Crosswordland and because they will never be visible in an answer, I do not always care about these deeper thoughts, I’m afraid.
“Gents”, “Gent’s” or “Gents’ ” – in the end they all lead to GENTS in the grid.
That is, if you don’t object because of the ‘value’ of the apostrophe.
And you do at times, I guess.

Never read a book about The Rules, but there must be rules or at least conventions for these situations.
I’m becoming curious now.
Or maybe a ‘professional’ could help out?

[The Rules? Have to learn those of cricket, rugby and golf too, then - very useful for solving a (broadsheet) crossword ]