Hampshire = Deneuve + Dunaway + Bujold. Is this true ?

Long before the shooting of "Malpertuis" I remember reading in a newspaper there were many possible castings. Back in 1970 it looks like Faye Dunaway, Catherine Deneuve and Geneviève Bujold were to star together (each one playing one of the three characters finally played by Susan Hampshire). I have to admit I don't know if this is true. If it is I guess why this casting was changed : in 1970 Dunaway just broke up with Mastroianni who immediately fell in love with Deneuve...