text: So I think you mean that this line (link below) needs to be divided into two, then named differently north and south of Crichton Street? That would be the process. Cut the line in two at Crichton Street. Add the tag 'name' with the value 'Chapel Street' on one,  and 'name' with 'Potterrow' on the other. Or confirm that this is what you need and someone can do this for you in a few seconds. 