In 1759, a Sarah Davis wrote her will and named her sister Mary Wright. Could this be Mrs. James Wright? Yes. Does it prove that this Mary Davis married James Wright? No.
Along with the Beals will, the Davis will could refer to the Mary in question. However, neither document by itself or together offer proof.
I f more solid evidence were to surface, these wills could offer supporting evidence. Standing alone they are convenient, but unsubstantiated, documents trying to prove a theory.