C# - Adding A Control To A List Of Controls Dynamically?

I have a web page where users need to enter customer contact information. They could enter from 0 to an infinite number of contacts.

I created this page code on page:

<ajaxToolkit:ToolkitScriptManager runat="Server" EnablePartialRendering="true" ID="ScriptManager1" />
<asp:PlaceHolder ID="phCustomerContacts" runat="server" EnableViewState="true">/asp:PlaceHolder>
<asp:LinkButton ID="btnAddContact" runat="server" OnClick="btnAddContact_Click" CssClass="LinkButton" Text="Add Contact"/>

In my code behind I added this:

public void btnAddContact_Click(object sender, EventArgs e)
{
IList<CustomerContactProfile> customerContacts = new List<CustomerContactProfile>();
if (ViewState["CustomerContactList"] != null)
customerContacts = (List<CustomerContactProfile>)ViewState["CustomerContactList"];
CustomerContactProfile contactProfile = (CustomerContactProfile)LoadControl("~/Controls/Embedded/CustomerContactProfile.ascx");
customerContacts.Add(contactProfile);
foreach (CustomerContactProfile contact in customerContacts)
phCustomerContacts.Controls.Add(contact);
ViewState["CustomerContactList"] = customerContacts;
}

This code doesn't work because the ViewState can't handle storing all of that control data. However, I cannot think of another way to store the controls that were already added.

The viewstate of the asp:PlaceHolder control doesn't save anything and I need the controls to be saved so that if a user puts in some data to the first control that the data isn't lost when they add a second one and so on.