Solved
is it possible to file with my same account my son/daughters' federal and state tax return or is it easier to create an entire different profile?
No. You will need to create a new user id when starting a new return as using the same account will overwrite the return already filed or started. Please see the following TurboTax FAQ on how to start another return in TurboTax Online:
https://ttlc.intuit.com/replies/3288574
Enter your E-mail address. We'll send you an e-mail with instructions to reset your password.