One of the main drawbacks with the Club Registrations system was the inability to add Individuals to a Cart after it had been checked out.  This caused problems when registrants failed to read instructions and did not register all of their family members or as otherwise instructed.  Ideally the best solution involves allowing the registrants to come back and edit their Carts and correct both missing Individuals as well as other registration changes.  This solutions is quite complex and is something that Zone4 is working towards with version 2 of the registration system now in development.  In the interim, the ability to add Individuals has been added to the admin Reports section.  When you click the Details link to view the Individuals you will see a link in the upper left of the Cart called "Add Ind".  Clicking this will refresh the page and add a new Individual blank row to that Cart.  You can then click on each of the fields in that row to edit and save the data the same as you would edit any other individual or cart data.  This method is a little slower than other potential interfaces but it keeps everything simple and takes advantage of the Adjustments architecture which keeps track of fee field changes so you know how much money is outstanding for each Cart.