Sure you can set up more accounts. I have several online accounts to test in to answer questions.
The Online version is only good for 1 return. But you can use the same email address for 5 accounts. You don't have to pay unless you want to print or file a return.
How to start another return in the Online version
https://ttlc.intuit.com/community/using-turbotax/help/how-do-i-start-another-return-in-turbotax-onli...
