Elizabeth Meade and Amelia Blake were in the same circle and most likely grew up together in Chance Harbor.
Elizabeth Meade is the mother of Diana Meade and one night stand of John Blackwell.
Amelia Blake is the mother of Cassie Blake and the late girlfriend of John Blackwell.
They were friends.
While Amelia was with John,John had an affair with Elizabeth.
When the fire at the boating house happened Elizabeth died while Amelia made it out,and everyone thought John had died until Cassie had a vision.