Enforcing parent-child relationship in C# and .Net

Question

Let\'s take the following two classes:

public class CollectionOfChildren
{
    public Child this[int index] { get; }
    public void Add(Child c);
}

public          


        

Answer 1

public class CollectionOfChildren
{
    public Child this[int index] { get; }
    public void Add(Child c) {
        c.Parent = this;
        innerCollection.Add(c);
    }
}

public class Child
{
    public CollectionOfChildren Parent { get; internal set; }
}