Rebecca: Sorry to take a year to reply! I just haven't checked this forum in a long time. ADK's book gives very little information about James (Jacobus) Rosekrans. The full entry reads as follows:
JANE KEATOR, b. ca. 1737, Rochester twp; m. JACOBUS (JAMES) ROSEKRANS, JR. b. ca. 1731, s. JACOBUS ROSEKRANS bpt. 17 March 1706 (Old Dutch Church, Kingston) and Sara Decker. He served UCM3 (3rd Regiment, Ulster County Militia). Minisink resident. Children:
1. Jane, bpt. 10 May 1758 2. Jacobus (James), bpt. 3 Aug. 1760 3. Jeremias, bpt. 18 Nov 1762 4. Engeltje (Angelica), bpt. 2 Sept 1767 5. Levy, bpt. 3 Apr 1770 6. John, bpt. 1 Nov 1780
Not much help in your particular quest, I'm afraid.