Fale cheque dishonourment 138 case

Hi My friend owns a company where a trustworthy employee in purchase deptt. had acess to blank cheques signed by him for purchasing products. gradually he left the company and stole few cheques and presented to bank later . On knowing this the owner issued “stop payment” directive to bank. However the person filled a case under 138 NI act against the owner saying he was entitled to payment as ahe was a partner in company, but was refused, which was wrong. He had 4 cheques and filed 4 seperate cases for same In 2 cases the decision was favourable to owner as he could not prove that he was a partner, however in 3rd case my friend has been convicted and directed to pay and 1 yr imprisonment. One case still pending. the earlier 2 cases were with one judge but this 3rd & 4th case was shifted to another judge’s court. 1. Please advise what to do, as we have to appeal against this judgement in one month. 2. Why was the earlier acquittal not considered 3. Can we appeal in high court or we have to appeal in same court.