David Zev Rosenberg - Name, Birth, Death

The New York, New York, U.S., Index to Death Certificates, 1862-1948 (per AncestryLibrary) includes a David Rosenberg. with details that include:
Age: 88 -- Birth Date: abt 1835 -- Birth Place: Russia -- Death Date: 17 Feb 1923 -- Hospital: Montefiore Hospital -- Death Place: New York City, Bronx, New York, USA -- Burial Date: 18 Feb 1923 -- Burial Place: MT Zion Ceme -- Father's Birth Place: Russia -- Mother's Birth Place: Russia -- Father: Jacob Rosenberg -- Mother: Tobe Rosenberg

One of the 1907 Obits for his mother, in that one named "Mrs. Tobey Rosenberg" https://www.newspapers.com/clip/87122782/tobey-rosenberg-died-1907/ mentions her husband's death, then says "Seven sons survive them, the oldest, David, being 81 years of age."
1907-81 = 1826

The Obit for Meyer E Rosenberg in 1920 says he was survived by five brothers, and the first listed is "David of New Jersey" -- if this is not the David mentioned there, then who is?

Were they off by a decade in Tobey's obit -- or in David's death record?

The Gravestone of Meyer H Rosen, who was father of Sophie (Rosen) Haimowitz, shows his father to be David Zev.
Meyer H Rosen father of Sophie (Rosen) Haimowitz is NOT the son of David Rosenberg who was son of Jacob and Toba (Fine) Rosenberg

"Zev" was introduced as David Rosenberg's middle name with this merge on Oct 6, 2021: https://www.geni.com/merge/view?revision_id=80796854510 -
So it is not a given name of David Rosenberg son of Jacob and Toba (Fine) Rosenberg but rather of David who is father of Meyer fzther of Sophie Haimowitz

"fzther" should be "father"

The Gravestone of Meyer H Rosen, who was father of Sophie (Rosen) Haimowitz, shows his father to be David Zev - confirming the middle name Zev belongs to that David.

Can one just undo that merge

Or does one first need to undo the more recent merge https://www.geni.com/merge/view?revision_id=80799971100
And then undo that merge https://www.geni.com/merge/view?revision_id=80796854510 ?