Mary Allen

Her name is included in her father's will (dated 5 Sep 1791), which means Abigail was alive in her 66th year. (There's no known I° source for Mary's death.) On page 79, Her father James dictated

“I give and bequeath unto my daughter Elizabeth Gorham five shillings and to my daughter Annah five shillings. Each of them having already had what I esteem theirs full portion out of my estate. And to my other seven daughters, namely Susannah, Hannah, Rebecca, Abigail, Mary, Sarah, and Ollive each thirty pounds to be paid by my wife in consideration of what is above given her…” @Ancestry.com.

Amos Otis chronicled the children of James and Susannah as follows:

1. Elizabeth b. 1713 married 1732 Col. John Gorham, and removed to Portland. He was a man of note in his day.
2. Susannah, born 1715, married 1735, Capt. Jonathan Davis, Jr., a shipmaster.
3. Anna, born 1718, married in 1736, John Davis, Jr.
4. Thomas, born 1719, married Elizabeth Sturgis 1752.
5. Hannah, born 1721, married 1743, Doctor Abner Hersey, an eminent physician, but most eccentric man.
6. Rebecca, born 1723, married 1742 Rev. Josiah Crocker of Taunton.
7. Abigail born 1725, (an Abia Allin married Seth Cushman of Dartmouth).
8. Mary, born 1727, married 1751, Nymphas Marston, Esq.
9. James, born 1729, married 1752, Lydia Marston.
10. Sarah, born 1730, married 1755, Mr. Justin Hubbard of Hingham.
11. Martha, born 1733, died 1740.
12. Olive, born 1735, married 1754, Capt. Samuel Sturgis, Jr.
Source: Otis, A. (1888) in Swift, C. F. (ed.) Genealogical Notes of Barnstable Families; Being a Reprint of the Amos Otis Papers originally published in The Barnstable Patriot. Barnstable, MA, USA: F. B. & F. P. Goss (The “Patriot” Press), p. 10. Available at: Archive.org.

Amos Otis: Primary Source Corrections & Additions

1. Elizabeth: b. 8 June 1713 according to "North America, Family Histories, 1500-2000" at Ancestry.com. "U.S. and International Marriage Records, 1560-1900" at Ancestry.com confirms the year of birth and marriage. m. John Gorham on 23 Jan 1732 is twice recorded at FamilySearch #1 and FamilySearch #2.
2. Susannah: Her birth year is confirmed by Thacher-Thatcher source at Ancestry.com. It also shows marriage to Jonathan Davis on 24 Apr 1735, which is confirmed by two I° sources: FamilySearch #1 and FamilySearch #2.
3. Anna: No I* source confirms day & month of birth. Only “U.S., Find a Grave Index, 1600s-Current” includes month & day but cites no source, and b. isn’t etched on headstone. “American Genealogical-Biographical Index (AGBI)” confirms b. year at Ancestry.com m. 1st: 1 Jan 1717 John Davis: "Massachusetts Marriages, 1695-1910, 1921-1924"– FamilySearch 1 and and FamilySearch 2 . m. 2nd: Hezekiah Gorham 28 Mar 1746: at Ancestry.com. “"U.S. and International Marriage Records, 1560-1900" confirms b. year & m. year at Ancestry.com. Two sources show her with 1st married surname. m. Hezekiah Gorham 28 Mar 1746: FamilySearch 1 and FamilySearch 2. and “International Marriage Records, 1560-1900” at Ancestry.com confirms b. year & m. year.
4. Thomas: b. 8 Nov 1719 proved by “Massachusetts, U.S., Town and Vital Records, 1620-1988” at Ancestry.com. m. 19 Apr 1752 as proven at FamilySearch #1 and FamilySearch #2. He is the primary heir of his father's estate as evidenced in the posted Will.
5. Hannah: b. 13 Dec 1721 proved by “Massachusetts, U.S., Town and Vital Records, 1620-1988” at Ancestry.com. m. Abner Hersey 3 Oct 1743 as proved by FamilySearch #1 and FamilySearch #2.
6. Rebecca: b. 24 Nov 1723. “North America, Family Histories, 1500-2000” at Ancestry.com provides day & mo. of birth (includes d.). “American Genealogical-Biographical Index (AGBI)” at Ancestry.com. confirms b. year. m. 28 Jul 1742 per primary sources at FamilySearch #1 and FamilySearch #2 . “North America, Family Histories, 1500-2000” at Ancestry.com concurs. “Massachusetts, U.S., Compiled Birth, Marriage, and Death Records” shows m. 27 Jul 1742, at Ancestry.com
7. Abigail: b. 7 Jun 1725 per “Massachusetts, U.S., Town and Vital Records, 1620-1988” at Ancestry.com. She was alive in her 66th year when her father dictated his Will. No record of marriage or death associated to parentage. It's possible she may have removed to Watertown, Middlesex, MA and died there 28 Apr 1703. However, though nothing else in that original burial record at FamilySearch shows parentage.
8. Mary: There’s no extant I° source shows birth-to-parentage. Therefore, 1727 given by Otis presides as II° source. She was alive in 5 Sep 1691, when her father’s will was dictated. She was age 64 at the time. Extant primary sources do not prove that either she or Nymphas Marston ever married.
9. James: b. 1 Dec 1729 as proved by “Massachusetts, U.S., Town and Vital Records, 1620-1988” at Ancestry.com. m. 7 Jan 1752 as proven by two I° indexed sources at FamilySearch #1 and FamilySearch #2.
10. Sarah: b. 21 Dec 1730 confirmed by “Massachusetts, U.S., Town and Vital Records, 1620-1988” at Ancestry.com. m. 14 Dec 1755 Justin Hubbard (unknown parentage) confirmed by "Massachusetts Marriages, 1695-1910, 1921-1924" at FamilySearch. Sarah was age 61 when her father included her in his 1791 Will.
11. Martha: b. 1732 per "Massachusetts, U.S., Town and Vital Records, 1620-1988" at Ancestry.com; also d. 21 Jun 1736 as confirmed by FamilySearch index record.
12. Olive: b. 18 Dec 1735 confirmed by “Massachusetts, U.S., Town and Vital Records, 1620-1988” at Ancestry.com. m. Samuel Sturgis on 28 Nov 1744 confirmed by "Massachusetts, Town Clerk, Vital and Town Records, 1626-2001" at FamilySearch #1, at FamilySearch #2, and at FamilySearch #3.