In the novel Taken at the Flood, Marjorie Macrae is the mother of Joan. She used to be Adela Marchmont's best friend and is presumably her peer.
Adela suggests to her daughter Lynn that they should make Joan the head bridesmaid at Lynn's wedding to Rowley, lest Marjorie be hurt. Lynn refuses, as she has always hated Joan and it is, after all, her own wedding.