I used to be able to file more than one return with TurboTax, but using TT Live, it doesn't seem to give me that option. Need to file an extension for my brother. Tips?

You cannot do more than one return with the on-line versions of TT. Do do a 2nd return, you must open another account.  Your brother mat qualify for the free version*. 

If you use the desktop/download/CD versions, you can do any number of  returns, but are limited to 5 e-filings.

TurboTax also has another free product called the Free File Edition (not to be confused with the regular Free Edition).  It has free Federal preparation and free State preparation. There is no e-filing fee. It is not available after October 15

The Free file Edition can handle a 1099-NEC or 1099-MISC.

The Free file Edition is more fully-featured than the regular Free Edition.  The Free File Edition can prepare Schedule A, C, D, E, and F that the Free Edition cannot. 

To qualify for free 2020 federal and state tax returns through the IRS Free File Program delivered by TurboTax, you just need to meet one of these requirements:

• Your 2020 household AGI is $39,000 or less;
• You qualify for the Earned Income Tax Credit (EITC); or
• In 2020, you served as active duty military (including Reservists and National Guard) with a maximum AGI of $72,000, and you have a military-issued W-2.

The FREE FILE Edition is located at:
https://turbotax.intuit.com/taxfreedom

How to switch and start over in Free file Edition
https://ttlc.intuit.com/questions/2026912-how-do-i-switch-to-turbotax-freedom-edition