With TurboTax online, you can only do one return. You will have to open a different account for a 2nd person.
For multiple family members, you may want to consider download/desktop software.
To switch from on-line to desktop:
Even before you pay for the online version you can switch to the desktop version and you won't have to re-enter your information. To continue in the desktop version see this
https://ttlc.intuit.com/community/choosing-a-product/help/how-do-i-switch-from-turbotax-online-to-th...
