Just checked in with MH@ SIN. Since no one was queuing up behind me, took the opportunity to chat with the agent (SATS employee) after I had my boarding passes .. 'Same booking, of course lah, to oneworld - even if separate booking/tickets, can can, some other cases also can, like if Emirates booking'. Was surprised at the last bit, but possibly post their strategic tie up.

Just to cover ground for the future, I then went to the lady at the ticketing desk by the side of check in row- the only person in an MH dress around, and she confirmed that it would not be a problem checking through to a oneworld carrier, even across bookings.

I know this flies in the face of Rami's experience in KUL this week, but I'd be willing to risk this- armed with a polite persistence and a grab of MH's page showing that the policy is to through check- the one that I linked to earlier (btw the page was updated sometime late 2015/earlier this year, and not in July 2014- that was only the reference to the mandatory kiosk check in..source:archive.org).