SOLVED. ghost sisters [s]

[Emily]

I think this was a children's book or a young adult book...there are twin sisters and one of them died when they were little and the other one realizes that she is actually the other twin (not the one she thought she was) and she had somehow accidentally killed her sister? and her sister comes back as a ghost when they're older....I really cant remember that well. Any suggestions would help, i know it had the word sister in the title and it was probably written in the 80s or 90s. Thank you!

[Jackie "the Librarian"]

I think you are looking for
Haunted Sister
by Lael Littke.

[Emily]

yes! thank you!