E-filing multiple tax returns

Every year I file my tax returns using TurboTax. I only had to buy the CD, but I never had to pay an additional e-fling fee. This year is different. I had to purchase a license code plus I had to pay to e-file my returns. In prior years, I was able to file my mother's tax returns and my stepson's tax returns using the same CD, but this year, TurboTax did not give me that option.  Why? I just filed my taxes, and I am trying to file my mother's taxes, but TurboTax won't let me.  Why?