Have no record of William. Have this information that PROBABLY pertains to Robert Edwards:

Will for Joseph Edwards, SM Co., 3 May 1746, p.3 June 1746. Child: Joseph, Benj., Stourton, John, Josias. Wife Mary Wit: Melvill Lock (Locke), John Edwards, Robert Edwards 24.423, Calendar of Wills, Vol. 9

Robert may have had more brothers then John and Joseph. A Robert and John are in Montgomery Co. Md. abt. 1790-1800. Robert has a grandaughter - Jane Edwards born of Joseph in Edwards Ferry Montgomery Co. Md in 1814. Seems this line moves West in Charles Co., Md. and North also. Have no evidence of them in Virgina at this time. They are in counties bordering with Va.