Correct me if I'm ok to give this advice to someone.

Non O multi enter before date is say end of October.

Go out and come back in the last week of September and get 90 days, expires sometime near the end of December.

Go on two weeks holiday at the start of November and get a re-entry permit at the airport.

On return from the holiday will be stamped back in until the same date in December, ie the 90 day date given at the end of September.

Thanks for answers.

What you wrote is correct.

What you wrote is correct.

Thanks I'll let him know.

I just wasn't sure about the re-entry applying on the final 90 as obviously the visa has expired.

After you enter the country the visas validity means nothing since you are then on a permit to stay.