GARRETTS in AL from SC

We are searching for information on four brothers who came to central Alabama (Lowndes County ) their names were Silas(b1803),Joe(b1799 d 1876 ), Caswell (b?) and John (b?)...we are descended from Joe.They came to Alabama from Charleston South Carolina but we are unable to find any information about them or their parents..I think they are somehow connected to Thomas Garrett II, from Delaware (b1652 d 1734) who had three sons Silas,Joe,and John but we cannot find the connection. Any help would be appreciated.We also have some information regarding Garretts in Alabama who are descended from these four brothers, but we are searching for more.There is a GARRETT family reunion held the last sunday in July every year.