Would be highly unlikely that she was a child of William & Delilah as they were married in 1782. If anything this might be a sister. It could be Martha who I have listed as being married to George Bruton, or Elizabeth b abt 1764 are it might be Bethenia b. abt 1757. Are you famaliar with the Addington association? Are you able to go forward from Margaret with some names, We may be able to tie in the family that way.