Thank you both so much, that's great to know.
@BirdsBeesTrees, hi! I recognise you from the peafowl forum. I also have peafowl.
So, after lots of reading and advice from you lovelies, I have come up with a plan. I was worried about moving her because the delay in setting something up would prolong her time sitting even more. However, I know I also can't leave her in her current situation because the Australorps are really messing with her eggs and it's just not working. I would hate to start her on fresh eggs only to have that go wrong as well.
My plan is to make some modifications to the flock arrangements that will cause minimum disruption to her but may take some time. So instead of waiting until things are sorted and then making her start the whole 21 days from that point, I've decided to start some in the incubator now and swap them out with her duds as soon as it's suitable when things are settled.
Assuming all goes well, her time sitting will only be extended by 10 days if I start them right now. That will give her a new hatch date of 14th May. The other benefit to this is that if the changes I make in the flock do stress her and she breaks, I can just finish incubating them myself.
To those experienced, does this sound like a viable option? Also, how many to do? I was thinking about 10?