In the CD/Download version of TurboTax, you can prepare as many federal returns as you want. Up to five can be e-filed. Additional returns must be printed and mailed.
You can also use TurboTax Online or the mobile app to prepare multiple returns, but each return requires its own unique login and must be paid for separately (if the return doesn't qualify for Free Edition).
Most customers who need to file separate returns for family members find that the CD/Download version is more economical.