Supplementary agreements can be signed, or changes can be made according to the specific conditions of the previous two trainings. I noticed that you added a service period later. In this regard, I suggest you carefully agree on the service period. "Labor Contract Law" and "Implementation Regulations" have strict requirements on the service period. You must engage in professional and technical training before you can carry out the service period. In addition, your company should consider the rationality of an employee's arrangement of training more than twice in a relatively fixed time. If you need to do it together, you can arrange the service period in a unified way in the changed agreement and allocate the liability for breach of contract reasonably.