Aunt Muriel

Aunt Muriel is the aunt of Molly Prewett, aunt-in-law to Arthur Weasley, and maternal grandaunt to the Weasley children: Bill, Charlie, Percy, Fred, George, Ronald, and Ginny.

Family Tree
Aunt Muriel married Mr. Parkington, having only one known child: Mordred Parkington. Mordred married Evaine, having only one known child, Malfalda Prewett. Malfalda is the third cousin of Molly Prewett, and third cousin-in-law of Arthur Weasley.

As It Continues
We expect that her family tree will expand soon.