Hello,
I am a member of the A3 program, thus I am putting my question in here (even if my question might be wrong here).

I am planing (longterm) following itenary
Copenhagen-Hongkong-Taipei-Hongkong-Copenhagen
Longhaul on SAS, connecting to/from Taipei is with Cathay.

The flight would be booked on ONE Ticket (important), so my question is as simple as ...

Can I credit SAS flights to my A3 FFP and
can I separately credit the CX flights to my other FFP (like BA Executive Club) as A3 doesnt acknowledge any CX flight miles (Star Alliance vv OneWorld Alliance).

I have never encountered such situation and the Internet doesnt give me any proper answers.

And yes, of course I can .... on those little gained Avios - however it would be an easy 80 TP (as my company would let me sit in Business-class.

Thank you for answers

Add your A3 number to the reservation and SAS miles will (hopefully) post automatically. You can then retroclaim the CX miles from your BAEC account.

Which code are the CX flights under?

Each part of the trip can be credited to it own program. A3 won't be able to credit the CX flights. They can be claimed to BA later or you can try and get the second FFP number on the booking. It can be easily done at the airport.

You can credit any flights on any star alliance carrier to any other star alliance carrier.
You can credit any flights on any oneworld carrier to any other oneworld carrier
Same with skyteam

You cannot transfer miles from one program to another (with a few exceptions - avios is a prominent one)

Depending on your fare class, one program may be more advantageous than another. Check here: https://www.wheretocredit.com/

That.

Are the CX flights with a CX flight number? If they have a SAS flight number it may be more difficult to credit those (I'm not exactly sure what the oneworld rules are regarding codeshares). I'm assuming the SAS flights are under SAS flight numbers for the credit to Aegean to take place.

For OW it should be seen as a CX flight as they are the operator. If they were both *A then there could be some mismatches between booking classes. Usually, a cross alliance booking don't have the issue. Also I think the only codeshares SK in that part of the world are SQ to Australia. The rest are more or less the minimum that *A offers