You can do your 3-sector ticket (Hometown - JFK - Europe1 - Europe2) as a OneWorld Multicarrier ticket, but it will need to have 2 non-CX airlines, which should be quite easily done (e.g. AA + BA).

https://www.asiamiles.com/en/terms-a...er-awards.html

There's a thread on OneWorld Multicarrier awards:

​​​​​​​https://www.flyertalk.com/forum/cath...ing-ideas.html