Who is Charlotte from Something Blue and what is their importance?

Charlotte is one of the women Darcy befriends on her first day of change. Charlotte is sitting in a cafe with her baby daughter Natalie and her friend Meg when Darcy smiles at her and inquires about Natalie. Charlotte invites Darcy to their table and is thrilled to hear Darcy is expecting. Though Charlotte is married, she finds nothing wrong with Darcy's single status. She even has a chap in mind to introduce to Darcy, as well as a new doctor and job prospect.