Pico's attempt to transfer his contract duties to Sven, an unknow sous-chef, will probably be declined. If Rhoda paid Pico for the lessons and they had the exchange of money for services, he is in charge of completing the lessons with Rhoda. In some situations where both parties agree to a change in sessions it may be allowed, but without futher information, we have to assume that Rhoda wants the lessons with Pico due to him being a famous chef.