You can have a different attorney represent you in your appeal than you did at trial. An appeal is very different than a trial and requires a different set of skills. The research and writing component of an appeal is extremely time-consuming. There is also a completely different set of procedural rules, and the consequence for non-compliance may be dismissal of the appeal. Often, it is a good idea to hire appellate counsel with experience in appellate advocacy. If your trial counsel is experienced in appellate advocacy, it is to your benefit to retain them for the appeal as they are familiar with the issues.