Originally Posted by
haapalainen
In addition to the Marhaba lounge, she has plenty of other lounge options with a business class boarding pass. Any oneworld operated lounge will let her in, and in Singapore those are Qatar Airways lounge, British Airways lounge, Qantas business class lounge and Cathay Pacific lounge. She can even try them all if she wants to.
Too bad Finnair is trying its best to not let passengers know about the oneworld lounge rules.

The CX Lounge is in T4 - the journey for which I wouldn't recommend unless you're really familiar with Changi/Terminal hopping.
Regards,
BD