I probably have your Ann.Two brothers from the Massachusetts Churchill family moved to Chittenden, Vermont, in about 1785.They were John and Isaac, sons of Ebenezer.Their line of descent from John of Plymouth, the immigrant ancestor, was William, William, and Ebenezer.Both were married at the time of their move, and Isaac's oldest son was Michael, born January 26, 1766, who married Lucy Dodge of Brandon, Vermont.Michael is number 281 in the 1903 book "Churchill Family in America" (CFA).
Michael was born in Plympton, Massachusetts (the CFA entry on Michael is wrong with respect to his birth place; it is given correctly in the entry for his father Isaac, no. 119).Nineteen at the time his family moved to Chittenden, both his age and the birthplace of his wife make it virtually certain Michael moved with them.At some point he moved to St. Lawrence County, New York.CFA states, "After much research I have just found a probable descendant of the eldest son of this family at Brasher Falls, N.Y. (May 29, 1903)."
Nine children are listed, with a note "probably not in proper order of birth."Child no. 5 is Anna and child no. 6 is Diana, so one of these two is quite probably the Ann you are seeking.
Only two of the nine children were sons, the presumed eldest, Isaac, and the presumed youngest, William.There are no dates of birth or further information on any of the children (Note:CFA assigned the same number, 612, both to this William and to his first cousin William.The information in CFA is on the first cousin).
It appears that St. Lawrence County, New York, might be the place to search for a marriage record to confirm that your Ann was of this family.New York has very good genealogical records.