Under Her Control

First I was confused why would they sign a contract if it was not enforceable since it wasn't legal. These two women have a lawyer draft a contract that he says is illegal, yet he advises them to sign it. Why? What lawyer would have his client sign an illegal contract? That made no sense to me at all. Second, not sure how the new borns are documented in Spain but how did they plan to legitimize this baby? The doctor would forge the birth certificate who the mother is? That made no sense to me. All these professionals would literally risk breaking the law for a baby? The whole movie made no sense.