Hi

First time redeeming miles from Asia Miles, and hitting some bumps. I have been watching award space on HKG-YVR like a hawk for quite some time. AM had been consistently releasing 5J awards on this route until they announced the devaluation last month. I need 4 seats. There are now only 2J awards available. I was prepared to "pay up" with Priority Awards (i.e. 2 standard and 2 priority). However, after I booked 2 standard awards, even the priority awards on the same flight are now showing "not available". So I am now unsure what I could do, except to fly the other half of the family on a different flight or day.

Questions:
1. Is it always the case that when the standard award gets booked, the priority award vanishes too? This seems wierd.
2. How do I make an award change online (so to save fees), in case I could book the second set of standard awards on another flight and priority awards are available? Maybe I'm dense, but I couldnt locate a "change award" button or drop down menu.

Thanks!