She would add all income on the same tax return.  If she received W-2, here's how to enter multiple W-2s:

After you enter the first W2 information, it will ask you if you'd like to enter a second W2. 

If you've already entered one and need to get back there to enter an additional W2, you can get there by the following steps:

1.  Log in to TurboTax Online and click Continue to to open your return (if it is not already open)
2. Click on Federal Taxes, and then click Wages & Income
3. Click on I'll choose what I work on.
4. On the summary page, look for the Wages and Salaries section.
5. Under this, it should list W2 and then Wages & Salaries. Click on the Update/Start button  to the right of this.
6. Follow the interview instructions to add each of your W2s.

All income from all sources received in a tax year are reported on *ONE* tax return.

Every W-2 that you received must be reported on your tax return, even if they are for small amounts.  Remember that each one of those W-2’s has your Social Security number on it, and that income was reported to the IRS by the employer.  You do not want to get in trouble with the IRS for under-reporting your income.

ALL of your W-2’s must be entered on the SAME tax return.  After you enter the first one, you click Add Another W-2.