This is not possible without an architectural change. You either need to have the separate line items spawn/update/delete single documents that can be displayed in views in the manner that you want, or you need to have users create the separate documents and have the main form display the information in the way you are doing it now (multivalue fields, etc.).
I’ve worked at this issue for about 8 years and have no other solution. Based on your current architecture, it can’t be done.