Something Borrowed books?

I have read "Something Borrowed" and I am finishing up "Something Blue." When I went to order the other books in what I thought was a series, (Baby Proof, Love the one You're With, and Heart of the Matter)I noticed that they feature totally unrelated characters. So are "Something Borrowed" and "Something Blue" the only two books about Darcy and Rachel? Are there more to come? And has anyone read the other books? If so, are they as good as the first two? Thanks!!