In his will dated 16 February 1709/10, David Lawrence named a number of family members including "my brother Benjamin Taylor." [New Hampshire State Papers 31:649-51]. One of the witnesses to David's will was William Taylor who signed by mark. There are three ways for David Lawrence and Benjamin Taylor to be brothers in the sense of familial connection: (i) David married Benjamin's sister; (ii) Benjamin married David's sister; or (iii) David and Benjamin married sisters.
Benjamin Taylor was the son of William and Anne (Wythe) Taylor. Anne's last name is variantly given as Wythe or Wise and she was the daughter of Humphrey and Susan (Pakeman) Wythe whose English origins were published by Clifford Stott in The American Genealogist in 1993. Anne (Wythe) Taylor was baptized 18 October 1632 at Woolverstone, England. This is important because it becomes one of the known dates by which we can place people chronologically in this family. The last of Anne's two Taylor children's births are given at Exeter: Mary on 26 October 1667 and Nathan on 5 February 1674. Her other Taylor children, including Benjamin must have been older. These dates rule out the possibility that David Lawrence married Mary Taylor as many, if not most, web sites have. David's eldest daughter Phebe married on 29 November 1696 at Stratham to Thomas Rawlings (Jr.). A woman born in 1667 would have had to marry at 14 (1681) and have a daughter at 15 (1682) who would in turn be only 14 when married in 1696. Not bloody likely.
That eliminates possibility #1 for the relationship between David Lawrence and Benjamin Taylor. Benjamin Taylor has three sons: Nathan, Benjamin and Edward. Based on their respective marriage and death dates they were born ca. 1696, ca. 1700 and ca. 1705. Benjamin and his wife, Rachel were therefore married ca. 1695. They in turn were born say ca. 1670 (give or take). Since Benjamin's birth is unrecorded between Mary and Nathan Taylor, it is more likely that he was born directly before Mary or ca. 1665. Rachel (---) is still born ca. 1670. David Lawrence is recorded first when he bought land in 1674. That probably makes him at least 21 years old and likely older since he had to have made the money to buy the land (one assumes). So David is born ca. 1650. This makes him about 60 when he makes his will. Although possible, if on opposite spectrums of the sibling list (i.e. David the eldest and Rachel the youngest), it doesn't seem that David and Rachel (---) were siblings either and seem to be of different generations.
That leaves us with the last possibility. David Lawrence and Benjamin Taylor married two women who themselves were sisters. So we are looking for two sisters, one named Mary born ca. 1655 and the other Rachel born ca. 1670, who are otherwise not given husbands in the literature available on 17th century New Hampshire people. It should be do-able. Of course, this brings up, yet again, my thoughts on better searching techniques for women. I should be able to search a database for a Rachel born 1665-1675 in New Hampshire and get a list. Then I can crosscheck it for those with a sister Mary. It should be (theoretically) easy to do.
David and Mary (---) Lawrence's daughter Phebe (Lawrence) Rawlings appears in my ancestry three times, so it would be great to figure out her mother's maiden name.
N.B. By using the imperfect way of searching Ancestry.com's trees year by year (1664-1675) for a Rachel, the only one available with a sister Mary are the daughters of John Bruster (i.e. Brewster) of Portsmouth, N.H. who left a will in 1691 wherein he mentions several daughters by first name only. Not a bad choice for research since the Bruster family has had practically no real research done on it since the mid 1800s when a notorious descendant forged deeds and altered real Portsmouth 17th century documents to tie John Bruster with the Mayflower passenger William Brewster. Most people either believe the malarkey or have a hard time sifting through the records for what is real and not forged.