Fix simple Model to render with order instead of PK in URL path

Classes are "Task" with related PK "Step" #example of the url structure: [login to view URL] #explaining the url: tasks/1 = (Task_pk=1)/1 = (step order =1)/ Note that I don't want to use the PK of the step. I want all steps in every task to display in the url as 1 - 2 - 3 Currently each step have a unique PK so for example task 1 have step 1-2-3 and task 2 have step 4-5-6 and so on. I want all tasks to have the steps 1 - 2 - 3 no matter how many tasks.