I was booking a HEL-KUL flight on AY website - I was offered a connection on 3K, but only with 3K code. Chatted with the agent, she said it's AY earning ONLY if it's AY coded. The was an AY codeshare on MH, which I finally took - gave also 30 mins more transfer time in SIN, the 3K transfer was a bit on the tight side.
Weird, though that the AY website doesn't offer codeshares on 3K.
BTW - to my great surprise the agent confirmed that there were upgrade availabilty both on HEL-SIN and HKG-HEL, so I booked Value and used the soon-to-expiry vouchers to move to the front of the bus. In the process I learned that Basic can be just 30€ cheaper for 50% less earning. No, thanks.
CX allowed me to book "preferred" seat for free (due to my OWE?) but MH seem to use another system (Galileo) with 5-digit PRNs, so that's still open.