public partial class Customer {

public Customer(){
Address = new Address ();
}
public int Type{ get; set; }
public string CustomerCode{ get; set; }
public string FirstName { get; set; }
public List<Address> Address{ get; set; }}

public partial class Address{
public string AddressTypeCode { get; set; }
public string CountryCode { get; set; }
}


kodun çalışacağı yerde:
Customer cs = new Customer();
cs.Address.Add(new Addres{AddressTypeCode ="x",CountryCode ="y" });