Looked for Jane Knox and Jane McDonald, nothing apeared right for me with that.
Found 1910 census-
1 --Jane McDonald b. abt 1840 Ireland- listed as Mother in law- in Newark, Ward 12, Essex Co New Jersey
2-- Jane McDonald b. abt 1839 Ireland listed as Head of house, in Pittsburgh Ward 7 Allegheny , PA.
3-- Jane McDonald b. abt. 1835 Ireland, listed as Mother- in Millis, Norfolk, MA
4-- Jane McDonald b. abt. 1840 Ireland Mother in law in Carbondale, Ward 5 Lackawanna , PA
5-- Jane McDonald b. abt. 1845 Ireland head of house- in Poughkeepsie, Ward 1, Dutchess Co. New York.
6-- Jane McDonald b. abt. 1846 Ireland head of house- in Manhattan Ward 21, New York , NY
7-- Jane McDonald b abt. 1831 Ireland head in Walpole Cheshire, NH.
Found 1920census -
Jane McDonald b abt 1840 Wales ? listed as a mother in law in Poughkeepsie, Ward 4 Dutchess Co., New York
Also did a look for JASPER KNOX,
I located this
1910 U.S.A.- census (taken the 10 or 19 of April)
Lived Manhatten Ward 22, New York, New York
White, Male Immigration year 1879 (NA)
Name Jasper W. Knox age 49 (abt 1861)birthplace Ireland
Head of house , Father b. Ireland, Mother born England ?
Married-
Spouse's name Mathill H ? age 46 (abt. 1964) b. Vermont. father Ireland, mother Maine
Looks like a lady named Margaret Christenhan (Christschen) lived with them, she is marked as a boarder
I would not know if this is your Jasper or not from that record.
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I did not see that Jasper in the 1900 census, does not mean hes not there, I just did not locate him is all.
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in 1880 census I located, in Pierce township, Page, Iowa a family of KNOX..
(who may/or may not- be part of the JASPER W. KNOX from the 1910 census )
here is what it has
John Knox- age 55 (abt 1825)b. Ireland father Widower retired farmer
W. J. Knox age 26 (abt. 1854 )b. Ireland single farmer (brother to head of house)
J.H. Knox age 25 (abt 1855) b. Ireland Married farmer (head of house)
Margaret E. Knox age 23 (abt 1857) b. Ohio (wife of head of house).
nothing- to confirm what you have really..
however kind of a start for your elimination
sorry, I could not be more help to you there !
LAH