Thanks for the wealth of info. in your last post. If you and I are connected, it appears as though it would be via the Sebastian and Anna Dumser you have arriving to the US ca.1830's/40's. We would share them as g-g-grandparents. We would be third cousins.
Everything seems to hinge on whether your g-grandfather (Sebastian) and my g-grandmother (Katherine/Katy) were siblings.
The evidence "for" that assumption would be they both had a "Sebastian" as a father, and are about 9 years apart in age (Katherine b.1859 NYC), and of 8 surviving children in 1900, you only know of 6...leaving room for 2 additional names.
The evidence "against" them as being brother and sister would be the span of childbearing years of their mother...1841-1859! (Not impossible, having been done before and since). Also, you say the mother's name was "Anna". I have her as "Marie". Then again, I could see her actual name as "Anna Marie", with various people referring to her using either name.
"Dempsey"??? Wow! Now that is a stretch! Here's a couple names to look up with misspellings from the 1880 census: DOMSER, Frank - West Turin, Lewis, NY. Also, DOMSER, Peter - NYC. Maybe you'll see a connection.
Bits & Pieces from NYC Directories:
1848-49 DUMSER, Geo. porterhouse 234 Fifth Ave. 1850-51 DUMSER, Geo. porterhouse 234 Fifth Ave. DUMSER, John, porterhouse 226 Second Ave. 1880-81 DAMSER, Jacob butcher 813 1st. Ave. DUMSER, ANNA M. widow of Sebastian 614 Fifth Av DUMSER, John cartman 614 Fifth Ave. DUMSER, Peter scavenger 606 E. 15th. St. DUMSER, Sebastian driver 609 E. 15th St. 1885-86 DAMSER, Jacob laborer 323 E. Houston
_1881 Certificate of Marriage NYC_
Dumser(Damser), Katharine(Katy) age: 22 Born: NYC Father: Sebastian Mother: Marie Doll [Address of Church was W. 53rd. St, probably near 10th or 11th ave. The family lived in the Hell's Kitchen neighborhood.]
_NYC Births 1891-1902_
DUMSAR, Sebastian b.d. 9 Oct. 1891 Certificate# 36238
DUMSER, Sebastian A.Mt. Vernon, NY b. 10 Aug. 1922 d. 22 April 2002
DUMSER, Sebastian b. 9 Oct. 1891 d. Jan 1965
BTW- All spellings of "Dumser" are as found in sources searched.
Geri...According to family oral history, Anna (or Anna Marie or Marie), lived to be 96 years old. Any idea if this is true?