All vital records in New York (except for NYC) prior to 1880 were originated and filed in the Town Clerk's office. After 1880 a copy was also sent to the State.
Since their burials were in Camden, I'm going to assume they died there as well. You'll have to contact the Camden Town Clerk, www.facebook.com/
and ask about a death record.
The Oneida County newspapers are at the New York State Library, www.nysl.nysed.gov/nysnp/all/433.htm
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The only thing I found about them was your family tree which looks very complete for Laban.
Prior to 1880 in New York (except for NYC) all vital records were recorded and filed at the Town Clerk's office. You can contact the New Hartford Town Clerk, www.townofnewhartfordny.gov/town-clerk
and ask if they have any birth, marriage and death records when the Olny family was living there.
I'd also contact the new Hartford Historical Society.
North Brookfield is in Madison County and you can do a Google search for their town clerk and historical society.
Another resource is the Oneida County Historical Society, www.oneidacountyhistory.org/
You'll find Oneida County newspapers at the New York State Library, www.nysl.nysed.gov/nysnp/all/433.htm
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