void billingEngine_EinvNodeAdded(object sender, MercatorUi.Engine.Gescom.BillingEngine.EinvNodeAddedEventArgs e)
{
    MercatorUi.Engine.Gescom.BillingEngine billingEngine = (MercatorUi.Engine.Gescom.BillingEngine)sender;
    if ((e.Node.Name == "cbc:ID") && (e.Node.ParentNode != null) && (e.Node.ParentNode.Name == "cac:PayeeFinancialAccount"))
    {
        e.Node.InnerText = "BE99999999999999";
    }
}