Spider is essentially right.
Meg is always the highest.
But, Amy and Beth mostly stay around the middle. I believe when its all the sisters (from high to low) its Meg-Beth-Amy.
But, when it comes to singing on their own, each sing a little higher, though Meg is the only one up in the 1st sop range.
Oh, and Elphie, it's
"I'm not BUILT for gowns."
"My friends have made the story of my life."
-Helen Keller