Hi,

Based on the testing i've done if you delete the sidebar it will not delete the head or the body of the linked list but if you use .Cascade it will delete the sidebar and the head but not the body, you can try it with the code below.

@Model
public final class Sidebar  {

    public var id: String?

    // bunch of stuff

    @Relationship(deleteRule: .cascade)
    var paragraph_: Paragraph?

    @Transient 
    public var last: Paragraph? {
        guard var paragraph = paragraph_ else {
          return nil
        }

        while let next = paragraph.next_ {
            paragraph = next
        }
        return paragraph
    }

    @Transient 
    public func append(value: String) {
        let newParagraph = Paragraph(id: value)
        if let lastParagraph = last {
            newParagraph.previous_ = lastParagraph
            lastParagraph.next_ = newParagraph
        } else {
          paragraph_ = newParagraph
        }
    }

    init(paragraph_: Paragraph? = nil) {
        self.paragraph_ = paragraph_
    }
}

@Model
public class Paragraph {

    public var id: String?

    var sidebar: Sidebar?
    var previous_: Paragraph?
    var next_: Paragraph?
    var attrStringData_: Data?

    init(id: String? = nil, sidebar: Sidebar? = nil, previous_: Paragraph? = nil, next_: Paragraph? = nil, attrStringData_: Data? = nil) {
        self.id = id
        self.sidebar = sidebar
        self.previous_ = previous_
        self.next_ = next_
        self.attrStringData_ = attrStringData_
    }
}

struct ContentView: View {
    @Environment(\.modelContext) var modelContext

    @Query<Sidebar> var sidebars: [Sidebar]
    @Query(sort: \Paragraph.id) var paragraphs: [Paragraph]

    var body: some View {
        NavigationStack {
            List {
                Section("Sidebars") {
                    ForEach(sidebars) { sidebar in
                        Text(sidebar.id ?? "")
                    }
                    .onDelete(perform: { indexSet in
                        delete(indexSet)
                    })
                }
            }

            List {
                Section("Paragraphs") {
                    ForEach(paragraphs) { paragraph in
                        Text(paragraph.id ?? "")
                    }
                }
            }
            .toolbar(content: {
                ToolbarItem(placement: .topBarTrailing) {
                    Button("Add Sample") {
                        try? modelContext.delete(model: Sidebar.self)
                        try? modelContext.delete(model: Paragraph.self)

                        let sidebar = Sidebar()
                        sidebar.id = "Sidebar"
                        modelContext.insert(sidebar)

                        let head = Paragraph(id: "Head Paragraph")
                        head.sidebar = sidebar
                        sidebar.paragraph_ = head

                        for i in 0..<5 {
                            sidebar.append(value: "Paragraph Body \(i)")
                        }

                    }
                }
            })
        }
    }

    func delete(_ indexSet: IndexSet) {
        for index in indexSet {
            let sidebar = sidebars[index]
            modelContext.delete(sidebar)
        }
    }
}