Validate user id in first step in createUserWizard and save it in the final step (both with onactivate method)

Hi, I've got a login page with createuserwizard. I've added a step on the begining so user inputs an ID which should be validated when the "Next" button is clicked" if it's ok user goes to the second (standard) step where he provides his username, password and email. When he clicks create user button the account is created but at the same time the ID from the first step is saved to a database. I have two databases, one standard asp.net for accounts and additional one where i want to write and read id number.
This is my code:
<%@ Page Title="" Language="C#" MasterPageFile="~/MasterPage.master" AutoEventWireup="true" CodeFile="Register.aspx.cs" Inherits="Register" %> <script runat="server"> </script> <asp:Content ID="Content1" ContentPlaceHolderID="head" Runat="Server"> </asp:Content> <asp:Content ID="Content2" ContentPlaceHolderID="ContentPlaceHolder1" Runat="Server"> <asp:CreateUserWiza ...