Update: Singapore Airlines were happy to change the ticket at check in at both Melbourne airport and changi. No fees required or questions asked and took them all of about 2 seconds. Spent the week stressing about nothing haha.
I booked 3 reward flights on SQ and Qatar for myself and my mum who has never been overseas before. Was supposed to be her birthday present. We are due to fly out on the 8th and I just realized her official passport name doesn't match the name she goes by. Her passport says Lea but I booked it...