Configuring Courses and Offerings

We have loaded courses and offerings for the customer as provided, but now they would like to change the links between some courses and offerings. One scenario for example is : Course 1 exists and has an Offering 1. A new Course 2 is created but it needs to now be assigned to the same Offering 1 (that is currently already assigned to another course). The Course 1 will then be enddated as it will no longer be used. Is there a way this can be achieved that we are missing, because when we try, we cannot assign same offerings to different courses?