TWO sisters were kicked, punched and slapped after being lured to premises in Yuen Long, the District Court heard yesterday. Tam Pui-fan, 19, and Tam Pui-yan, 18, were made to sign debt notes for $108,000, and told they would be forced to work as prostitutes to repay their ''debt''. Wong Chun-ming, also known as Ah Ming, 23; Fong Hoi-lun, also known as Kau Chai, 18; and Cheung Wai-tao, 21, were each found guilty of two counts of blackmail yesterday. Fong and Cheung, who originally faced two counts of wounding, were also found guilty of assault occasioning actual bodily harm. A fourth defendant Ma Hing-sin, 18, has pleaded guilty to two counts of assault occasioning actual bodily harm. Prosecuting counsel David MacKenzie-Ross said the two sisters were separately lured to Yuen Long premises on September 9 last year, where they were assaulted after Fong accused them both of playing him along. The pair later managed to leave the premises and alerted the police. In a separate case, Ma also admitted trying to pervert the course of public justice by threatening Tam Pui-yan. Deputy Judge Wright adjourned sentencing until January 25.