Once you have provided the details of the first defendant, click the green + button to add another defendant.
This will open a new defendant details tab. Enter the details for the defendant
A new menu navigation link for the new defendant will not be created at this time in the area circled above. If you need to add other details (eg. Vehicle;Insurance;Nominated Solicitor), please save the case and re-open it and the new defendant will be available in the Navigation menu.
When you re-open the case, the navigation will now show the other navigation links for the defendant allowing to enter the details.