Well, I personaly think that Sorsha is one of those names that doesn't really need a nickname, 1. because it's so short and 2. because it's so pretty already. I think Shorshy is rather cute but I also like Orrie / Orry,
Shay or Sha, maybe
Sasha because it's so close. WDYT? Other than these a nickname could come from a middle name or a personality trait or feature of the child, such as if she had red hair she could be called "
Red" or if her middle name was
Joy or
Jane you could call her S.J. or use her middle name as a nickname.