I agree that moving her in with unknown birds now would be a bad idea. Even my top of the flock birds cower and hide when they are moulting. They get all brave again when they have finished their moult.
Is the new coop "nicer" from a chicken perspective or a "human" perspective? Chickens don't really care if their lighting is Tiffany or Walmart
What are the improved amenities from a chicken perspective? Can you let her have access to both coops simultaneously? She might take a few days to decide the new one is preferable, though if (for example) the old one has more daytime ground level drafts and the new one doesn't she might choose to inhabit the new one.
And yeah, THIRTEEN years?!? That is a 100+ year old equivalent for sure. I don't know how long a girl that old will take to moult, my oldest 4 are only 6.5 years old.
Is the new coop "nicer" from a chicken perspective or a "human" perspective? Chickens don't really care if their lighting is Tiffany or Walmart

And yeah, THIRTEEN years?!? That is a 100+ year old equivalent for sure. I don't know how long a girl that old will take to moult, my oldest 4 are only 6.5 years old.