Online is only good for one return per account. You can use the same email address for 5 accounts.
How to start a new online return
https://ttlc.intuit.com/community/using-turbotax/help/how-do-i-start-another-return-in-turbotax-onli...
Or we can tell you how to switch to the Desktop program which can do multiple returns and has a What-If worksheet and other features over the Online version.
