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

Meg sits in a coffee house with Charlotte when Darcy is invited over by Charlotte. Meg is excited to hear Darcy is having a baby and divulges to Darcy that she and her husband are trying to have a baby. Meg is not as excited about introducing Simon to Darcy, as he is a ginger, but she acquiesces he is a good chap. Meg is happy to invite Darcy to her upcoming party as Darcy promises to be a new friend.