Who is Sarah Grimes Wilson from The Easter Parade: A Novel and what is their importance?

Sarah is Emily's older sister. When they are young, Sarah is the apple of her father's eye and this translates into a complicated relationship with her mother. Sarah's beauty and her apparent intelligence turns her into someone her sister desperately admires. Therefore, when Sarah marries, Emily assumes that Sarah has made the life for herself that all women should aspire to. However, Emily has never felt she is anything like Sarah; therefore, she does all she can not to follow in Sarah's footsteps.