Legal analysis: you can change lawyers halfway, because these are general agency contracts. If you are not satisfied with this lawyer, you can change to another lawyer. In the mediation stage, lawyers can intervene or not, because the purpose of mediation is to reach an agreement between the two parties, and lawyers can't completely replace the parties to make the final decision, so it doesn't matter whether lawyers intervene or not. Of course, the responsible lawyer will actively promote the perfect handling of things and will intervene.
Legal basis: Article 45 of the Criminal Procedure Law of People's Republic of China (PRC). During the trial, the defendant may refuse the defender to continue to defend him, or entrust another defender to defend him.