Is this anyway possible for PM Narendra Modi to inform BJP about his latest decision to ban INR 500 and INR 1000 notes beforehand ?

Such decisions are not made in a vacuum. I imagine word got out from the heights levels to the party leaders as the decision was made.

Modi could have done that if he chose to – it was a political decision to keep Indian citizens uninformed.

Most politicians like to wield their power without being question. He knew that if he announced it ahead of time, he would have been criticized a lot. So he did this as a fait accompli.

Politicians are not honest people.