David Baker was the great grandfather of Rollin C. Cooper and Thomas J. Cooper.

The Daughters of the American Revolution website shows the following information for David Baker:

• Service:  NEW JERSEY   

• Rank: LIEUTENANT

• Birth:  30 Nov 1751    ELIZABETHTOWN,  ESSEX CO, NEW JERSEY

• Death:  6 Mar 1833    MORRISTOWN, MORRIS CO, NEW JERSEY

• Service Description:  1) CAPT. WM. BRITTON, COL. OLIVER SPENCER

Another reference lists him as a Private rather than a Lieutenant.

1. David Baker married Phebe Wilcox who was born on June 18, 1756 in Elizabethtown,  New Jersey and died on September 30, 1835 in Morristown, New Jersey.  They were married on May 2, 1773 in New Jersey and had a child named  James Baker.

2. James Baker was born on March 18, 1779 in Morristown, Hanover, New Jersey.  He died at Lake Geneva, Wisconsin on October 19, 1851.  He married Elizabeth Price who was born on March 20, 1780 in Morristown, New Jersey and died on October 24, 1780 at Lake Geneva, Wisconsin.  They were married in 1799 in Morristown, New Jersey.  They had a child named Hannah Caroline Baker.

Sources:

1. DAR Genealogical Research System