I present you this rat's nest that I don't know how to resolve:

Mary Ann Polly Burdick (born Hancock).

MyHeritage Family Trees:
Burdick Family Site (23andMe), managed by Douglas Burdick (Contact)
Birth: Dec 22 1793 - Stonington, New London, Connecticut, United States
Death: Jan 25 1884 - Almond, Allegany, New York
Parents: Edward Hancock Iv, Nancy Hancock Iv (born Miner)
Siblings: Edward Hancox, Sally Ann Hancox, Sarah Hancox, Clement Miner Hancox, Joseph Wright Hancox, Joseph W Hancock, Eliza Hovey, Ethan Allen Hancox, Frances Maria Hancox
Husband: William Burdick
Children: William Stillman Burdick, Hubbard Smith Burdick, Nathan D Burdick, Clark C Burdick, Edward P Burdick, Emily Burdick, Mary Ann Burdick, John Hancock Burdick, Collins Cady Burdick, Charles P Burdick

I tried to start a discussion on Geni.com, but I don't think anyone using MyHeritage site ever visits Geni.com. My input was:

From "Supplement to Descendants of Robert Burdick of Rhode Island", Compiled by (Nellie Willard) Johnson, Author of the Genealogy, Norwich, NY, 1952-1953:
Page 162, "P. 117. No. 250. Mary called Polly Ann Hancock was the dau. of Nathan who d. Oxford, N.Y. Sep. 15, 1831; m. Stonington, Conn., in 1st. Cong. church, Dec. 1, 1784, Phebe Palmer, dau. of Rufus."

This conflicts with information found in Burdick Family Site (23andMe) Family Tree, managed by Douglas Burdick (contact), on MyHeritage.com, which states:
Mary Ann Polly Burdick (born Hancock)
MyHeritage Family Trees
Birth: Dec 22 1793 - Stonington, New London, Connecticut, United States Death: Jan 25 1884 - Almond, Allegany, New York Parents: Edward Hancock Iv, Nancy Hancock Iv (born Miner).

What is the support for the latter?

And finally:

http://www.burdickfamily.org/genealogy/getperson.php?personID=I20250&tree=bgen:
- She was a grandniece of John Hancock, the great patriot and statesman.
- Cr. for Polly's father's name is Emily R. Burdick, her grand daughter.
- Her father, Nathan, d. Oxford, N.Y., Sept. 15, 1831; m. Stonington, Conn., in 1st Cong. church, Dec. 1, 1784, Phebe Palmer, dau. of Rufus.
(Cr. Miss Emily Burdick, W.R.C. Home, Oxford, N.Y. and Mrs. Kaple per Pauline Kilbury, Hornell and Rochester, N.Y.) (See Sup. on P. 16.)

I found this information going through Geni.com. The parents for Mary Ann are different. I don't want to go the MyHeritage site for discussion because it is a pay site. Anyway you can think of to resolve this?

I don't have any problems with the description of tracing the true lineage of Mary Ann Burdick. What caught my eye is the emphasis on Mary Ann being a grand niece of John Hancock. Many years ago I delved into John Hancock's genealogy and found no possible evidence that he had a grand niece. Since then I have personally thought that Nellie Johnson had it wrong. So for me, that remains the unsolved question