There is an Olympic Airways flight (#37) which island hops on the way to Rhodes. It goes via Leros - Kalymnos - Kos.

I am undecided whether to fly to Kos or Rhodes. This is trip planning for mid-September.

If I book all the way through to Rhodes would it be possible to change plans nearer the time and say that I want to get off at Kos? How flexible is Olympic with this sort of change?

It should be possible. Check this: https://www.olympicair.com/en/Info/T...d_Reservations

I had already looked at this and it envisages change of date but not destination. I have written to Olympic but I may get a "formal" response laden with difficulties.
What I am after is local knowledge "out there" on the eastern islands. Perhaps the hotel on Astypalaia can have a word with a travel agent on his island.

I called Olympic and here is what i was told.

If you book a ticket to Rhodes, which is the longest and most expensive leg, you won't be allowed to get off in Kos, if you change your mind.

If you decide to fly to Kos instead of Rhodes, you will have to change your booking, which will be based on availability.

They also mentioned something about canceling one ticket and re booking, since flying to Kos would cost less, and there would have to be a refund.....

Thank you. I am not interested in a refund but only flexibility.