More DNA from Dunn and Dunlop Ancestors, Plus More?

Family Tree DNA notifies you when a "close" relative is found.  Based on whose account also received this email, I knew that the common ancestors would be in my father's Winterton/Dunn branch.

Family Tree DNA allows you to see the shared segments of DNA with anyone in your Family Finder results.  This person, who displayed his name, shares 13 segments of DNA totaling 323 centimorgans with my paternal grandfather's first cousin, D.W.  A check of the family tree showed the actual relationship between D.W. and this newly tested person as second cousins, once removed.  Their most recent common ancestors were Ezra Dunn (1821-1898) and Hermoin Dunlop (1827-1900) of New Jersey.  My line descends from their daughter, Catherine (1865-1944); the second cousin descends from another daughter, Violet (1873-1931).

Based on this view of the shared DNA, I can identify the mystery cousin from a year ago at 23andMe as a daughter or niece of this new match at Family Tree DNA.

Here are the problems:
1- This is a lot of DNA for second cousins to share.
2- The shared segment on chromosome 7 is shared by a fourth cousin from a different branch- Walling/Dey.

23andMe chromosome browser
Three segments of DNA shared by these fourth cousins, once removed.

Transcribed will of William Walling of Middleton, Monmouth County, New Jersey, 1823.
My line descends from the son William (1803-1870).
The fourth cousin whose DNA is featured above descends from the son Amos.

As I discussed back in 2015 when this Walling/Dey fourth cousin appeared, we need to triangulate these segments of DNA with other matches before we can decide if this is likely Walling/Dey DNA.  We cannot do this with this newly tested cousin because they are spread across companies.  The Walling/Dey cousin is on 23andMe and Ancestry.com (no chromosome browser), while this closer Dunn/Dunlop cousin is at Family Tree DNA.  If they both uploaded to GedMatch (for free!) we could see if they match each other on chromosome 7.  The next-generation cousin at 23andMe has not accepted my request to "share," so we cannot see the matching segments or compare to others.



The excessive DNA is caused by being related to this close Dunn/Dunlop cousin in one or more additional ways.  Possible explanations:

1-  One of his other ancestors not in the straight line of descent from Violet Dunn may be descended from our Walling/Dey branch.

2-  Ezra Dunn or Hermoin Dunlop may themselves have ancestors in common with William Walling and Rebecca Dey.  My inclination to locate this overlap (my first pedigree collapse!) would be in the ancestors of Margaret Combs (1795-1870), the mother of Hermoin Dunlop, because they were living in Monmouth County near Walling and Dey.  Hermoin's father, Joseph Dunlop (1797-1852), was possibly from Pennsylvania, while Ezra Dunn was in Trenton, New Jersey.  Go with a geographical match when trying to figure out these DNA connections.