Hi, I've done a search of the forums and the internet and couldn't find any answers, so hoping someone here might be able to help.

I've managed to book an outbound leg from LHR-SYD on Avios, but want to book SYD-LHR on the way back with a stop over. Typically one would just book SYD-LHR in one go 355 days in advance, but I wanted to stop over in SIN for a few days. What's the best way of doing this? Should I:
1) 355 days in advance, call up and add the SYD-SIN leg, then later call up 355 days in advance of the SIN-LHR leg?
2) 355 days in advance, call up and add a SYD-LHR leg, then later call up 355 days in advance of the SIN-LHR leg and change that leg only?