Richard and Cheng are partners of Sharp & Co., a hardware shop. Richard's friend, Allen went to Sharp & Co. to complain about a knife she bought from the shop three days ago. Richard became angry and stabbed Allen with the knife. Allen brought a charge against Richard for causing her grievous hurt. Cheng is worried that he would also be charged for causing grievous hurt since he is Richard's partner. Discuss whether Cheng is jointly liable or not. Your answer should be supported with one case law.