The client needed a registration system for students and their parents. They also needed an invoicing system.
I used three reputable plugins: Profile Builder, Sliced Invoices and Advanced Custom Fields. I had to extend the first two plugins as well as change a few of their features. Eventually, I combined all plugins. There is a registration page, a login page, and finally a profile page where users have access to their child's progress as well as see their invoices and their status.