Adding spouse in GSM 189 Application.

Dear all,

I have recently applied for GSM 189 visa, and now have been allotted a CO. My question is: Can I add my spouse (wife) as secondary applicant at this stage although I mentioned her as a non-migrating member earlier because her passport was not ready. Her IELTS score is 5.5
Kindly tell me the procedure to apply for spouse addition.

Thanks,
Ahsan