In this patriarchial society, the consent of Darcy's father to any marriage for his son would be necessary. Particularly for any match concerning the Darcy family estate and fortune. However, a woman of forceful personality could influence the choice of partner for her children, especially if by her own marriage settlement she controlled the property she brought into the family.(That's something else we don't know about Lady A) It seems likely Mr Darcy snr would know of any real wishes of Lady Anne in relation to a marriage with Anne de Bourgh (perhaps he was less keen on the idea than his wife?) Anyway, in relation to any planned merger, if alive, the consent of Darcy's father would be essential... Darcy does keep to himself doesn't he? And he so carefully shows no tendencies to any young lady. I wonder if that's why Darcy doesn't like to dance. ;)