Hi Susan Yes Rackley Island or Rackliff Island as it is now called is the one off Spruce Head. That area is loaded with members of the Rackliff(e) family
As far as what happened to John Davis I don't know and can't seem to find out. I did not know there were any children so I just assumed he died and Polly remarried. That was not an uncommon occurance it those days. The existance of your James adds a complication. I did check the 1810 census for James Chadwick and found one in Lincoln, Frendship that seems to fit. 1 male and 1 female 16-25 and 1 male under ten. The under 10 could be your James Davis. Does that seem possable based on the information that you have.