How wonderful Julia, congratulations.
I havent hatched a single egg this year (family llness) & looked after 13 babies for a friend, I was very broody & reluctant to give them back!
I had twins a few years ago. Just like yours, one had died early on. I didnt even spot it! The survivors egg sac unravelled like a turban
which I put down to catching on the sharp egg shell ! I had to tie it off & she remained bent up for a while, but she has straightened out & growing nicely now