How to modify replicator activity

Question

I'm using a Replicator Activity in my Workflow. I would like at some point, to modify the list I've given to InitialChildData.

I've tried to do something like :

this.replicatorActivity.InitialChildData[3] = "test4"

Hoping that when I would go in my ChildInitialized function it would change me the value of

e.InstanceData

But It didn't changed anything.

Does someone know how I could modify this variable ?

Thanks

Edit : that's my code for the moment

public Workflow1()
    {
        InitializeComponent();
    }

    public Guid workflowId = default(System.Guid);
    public SPWorkflowActivationProperties workflowProperties = new SPWorkflowActivationProperties();
    public ArrayList list = new ArrayList();


    private void Replicator_ChildInitialized(object sender, ReplicatorChildEventArgs e)
    {
        Console.WriteLine(e.InstanceData.ToString());
    }

    private void codeActivity1_ExecuteCode(object sender, EventArgs e)
    {
        if (this.replicatorActivity1.CurrentIndex == 0)
        {

            this.replicatorActivity1.InitialChildData[1] = "Test3";
            list[1] = "Test3";
        }
    }

    private void Replicator_Initialized(object sender, EventArgs e)
    {
        String test = "test";

        list.Add(test);
        list.Add(test);
        list.Add(test);
        list.Add(test);
    }