OOP composition

Question

I have a question regarding OOP composition.

Let's say that a mother has 0 or plus children, and a child has one and only one biologic mother.

To illustrate it, I did the following :

public class Mother : ObservableObject
{
    // [...]

    ObservableCollection<Child> Children {get; set;}
}

public class Child : ObservableObject
{
    public Child(Mother mother)
    {
        this.Mother = mother;

        // Adding the child to the mother's children collection
        mother.Children.Add(this);
    }

    public Mother Mother {get; set;}
}

but I wonder if it's okay to automatically add the child to the mother's collection, or if I should go with the following :

Mother mother = new Mother();

Child child = new Child(mother);
mother.Children.Add(child);

Thanks :)

Answer 1

I'd prefer,

public class Mother : ObservableObject
{
    // ...

    public Child GiveBirth()
    {
        var newBorn = new Child(this);
        this.Children.Add(newBorn);
        return newBorn;
    }

    // ...
}