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SurveyJS
Open-Source JSON Form Builder to Create Dynamic Forms Right in Your App. With SurveyJS form UI libraries, you can build and style forms in a fully-integrated drag & drop form builder, render them in your JS app, and store form submission data in any backend, inc. PHP, ASP.NET Core, and Node.js.
Perhaps one plugin I think might be very useful in your use is Breadcrumbs. It allows you to set up Parent > Child > Sibling relationships between notes using metadata, has a descendancy view (shows all notes in an outline that are related), it's own graph tailored to it's use, or can use Juggl for custom views. I'm sure there's more that isn't coming to my mind right now. But I think you'd find it helpful. The documentation is good, and there's even some YouTube videos on using it.