When you use Online TurboTax, you get one return per fee. Each return needs its own account and user ID. If you use the same account and user ID for a second return, you overwrite the first one and lose it forever.
https://turbotax.intuit.com/personal-taxes/online/
If you have multiple returns to prepare for various family members, desktop download software would be more cost effective.
You can prepare and e-file up to 5 Federal returns—more if you mail the additional ones. If you have multiple returns to prepare for family members, Desktop is more cost effective.
Desktop --unless you specifically buy federal Deluxe only from a retailer-- will include the software for one specific state. You can prepare as many returns for that state as the number of federal returns you prepare. E-filing state returns is an extra fee which can be avoided by printing and mailing the states. Additional--other--state software is an additional fee for the software.
No, the online programs only allow the user to file one return per account. Each user must set up his own separate account. The download version however allows up to 5 returns to be filed per program.
I have re-read your question and am still puzzled by it. Did you purchase the desktop download? If so, why are you asking about setting up a bunch of online accounts? You do not do that for desktop software. You just download the software to your own hard drive and use it from your own computer----there is no "logging in" to online accounts each time you prepare a return. When you have desktop, you open the software from your own hard drive, go up to File and click New Tax Return for any new return you need to start for a different family member. The returns will all be stored on your own hard drive. They will not be stored online.
for online a separate account is needed for each taxpayer. A unique ID is required but the same e-mail can be used
if you use one of the desktop apps, it's probably cheaper. One fee covers the federal and one state return but there is usually an additional fee for e-filing state. You can do as many returns as you want with no additional fee. You can save each of them. Turbotax automatically uses the taxpayer's name. You are limited to e-filing 5 returns. That's an IRS limit not a Turbotax limit.