I want to know the answer to the following question:
Which sister did Frédéric play duets with sometimes while being tutored at this time?
All the background I'm provided with is that "Fryderyk may have had some piano instruction from his mother, but his first professional music tutor, from 1816 to 1821, was the Czech pianist Wojciech Żywny.". Is that enough to answer the question?
Answer: no