 Piernas and escaleras on the table cannot be broken up to reuse the cards to form new combinations - they can only be added to.You cannot add to another player's piena or escalera until you have put down a pierna or escalera of your own.If the stock pile is exhausted, the cards in the discard pile (apart from its top card, which is left in place), are shuffled and stacked face down to form a new stock pile.