With TurboTax Online you can file up to 20 returns and you pay per return; so if you file taxes together they have to pay for the Premier amount of $34.99 each.
You need to create a spousal return when you start your return. You will have a question about if you want to produce your spouse's return a the same time as yours. If you already started your return, you can't go back to add her. Unfortunately, you will need to start over and create a new spousal return with her.
Thank you for choosing TurboTax.