have done this pairing two seasons on the trot, with 3 silver jills, never produced BEW'S only silvers, albino's and polecat, not saying it cant be done,
You won't.
The white of albinos and the white of BEWs has different origins.
Colour in animals is due to cells called 'melanocytes'. These produce melanin which gives the ferret its' colour. Albinos have melanocytes but they aren't 'switched on'. BEWs dont have melanocytes.