How can I do my daughters taxes, 1040EZ, first, then do mine all on the same account

[retiree]

Using the On-Line version, one of the features is that the  user ID/account can be used for ONE and only one tax return --e-filed or printed/mailed.  (Has always been this way)

If you need (or try) to prepare more than one return you MUST create a new user ID/account and pay for EACH return  --if you want to use the on-line version.  The same e-mail address can be used for multiple DIFFERENT account ID's.

If you try to prepare a second return using the same ID you will overwrite all data for the first return
and it will be lost forever; thus if the IRS challenges your first return you will no longer have a basis
to respond to questions.

Starting another return (with the Online version)
https://ttlc.intuit.com/questions/1894512-how-do-i-start-a-second-return-in-turbotax-online


Might be better (less expensive) If you are use the Desktop version (which you install on your own computer) simply open/launch the program and select the BLUE "Start a New Return" button (or select "New Return" under the "File" tab in the menu bar) near the center of the window; TTax should then save each return with a unique filename based on the first name listed on the actual return.  Multiple returns are no problem and no additional cost. The IRS limits you to 5 e-filed returns; however you can print and mail additional returns.

You can purchase CD (or Download) from TTax at this link:
https://turbotax.intuit.com/personal-taxes/?view=desktop

You should also be aware that many retailers (on-line and storefront) frequently sell TTax CDs and/or downloads for less.