Maybe someone can shed some light for me, I think maybe I've missed an opportunity in the way I booked my award flights for later this year.

I've got SYD-BKK and then BKK-SYD. I'm actually needing to get to Hanoi initially but will leave from BKK (travelling south and then back through cambodia)
I just booked the BKK return because I assumed that the same arriving/departing destination was required, but I notice some peoples itineraries look more complicated than that. But naturally now I'm trying to tee up the BKK-Hanoi flights at extra expense.

Was it possible for me to have actually just done the whole thing using the award booking?