You don't include their income on your return. It would only go on their return if they are required to file one. To file a separate return for your dependent you need to set up a new account. Online is only good for one return per account. You can use the same email address for 5 accounts.
Be sure on their return they check the box that says they can be claimed on someone else’s return. If their only income is W2 and under 14,600 they do not have to file a return except to get back any withholding taken out. If they got a 1099NEC or paid cash they have to file it as self employment no matter how small.
Filing requirements for a dependent
https://ttlc.intuit.com/community/children-dependents/help/do-i-need-to-file-my-own-taxes-if-i-m-a-d...