The mess starts with Elizabeth Mallory, whose third husband (AFTER 1485!) was "A" William Mallery or Mallory - but we don't know which one, and there were several men by that name. It seems highly unlikely that he was Sir William Mallory of Studley. There is no record of any children by this marriage.
Somebody has misfragged THREE William Mallorys onto the Studley line:
Sir William Mallory, of Studley (he belongs there)
Sir William Mallory, of Studley (misfragged into a duplicate)
William Mallory, Esq. (unnecessary duplicate)
In no case could Sir John Mallory, Knight, Sir William's heir and successor, have been a son of Elizabeth Le Bruyn, as he was born in 1473.
Sir John has been made into a quadrigamist, with four wives all living at the same time.
And beyond there it gets increasingly hideously snarled up.