sorry for your losses; horrible thing to happen.
How big is your Eglu, and in particular, has it more than one nest box? And why can't you wait for the eggs to hatch? 2 weeks is not long really. If there is a free nest box in the Eglu, I'd put the survivor with the broody; the latter may not be much company for a fortnight, but the survivor would know she was there and they'd be together through the night, and there would be a real flock again soon, and the chicks would be integrated from hatch. It seems simpler than trying to get and integrate new birds, which ought to be quarantined for at least 2 weeks anyway, so wouldn't provide instant company.