The poet Sylvia Plath was known to admire McCullers' work, and the unusual phrase "silver and exact", used by McCullers to describe a set of train tracks in the novel, is the first line of Plath's poem "Mirror".
I think the opening of Plath's novel The Bell Jar also offers a deliberate echo of The Member of the Wedding. This is The Bell Jar:
It was a queer, sultry summer, the summer they electrocuted the Rosenbergs, and I didn't know what I was doing in New York. I'm stupid about executions.
And this is The Member of the Wedding:
It happened that green and crazy summer when Frankie was twelve years old. This was the summer when for a long time she had not been a member. She belonged to no club and was a member of nothing in the world. Frankie had become an unjoined person who hung around in doorways, and she was afraid.
In both novels, the fact it is summer is a bold, declaratory statement. Both Esther and Frankie are depicted as outsiders: Esther doesn't know what she's doing in New York, while Frankie is an unjoined person belonging to no group. Esther describes herself, pejoratively, as stupid; Frankie is afraid: negative emotions are attached to each of them.
Moreover, Plath's use of "queer" in the opening line mirrors McCullers's use of the word on the first page of The Member of the Wedding, when Frankie's first words in the novel are: "It is so very queer... The way it all just happened."
It seems to me that Esther, created in 1963, is a deliberate echo of Frankie, written in 1946. At the very least, these remarkable young women would surely have found some affinity. If only one could have known the other.