If you are using TurboTax Online, you can still edit a return that hasn’t been NETFILEd, just by opening the return.

To add a T4 slip in online editions of TurboTax:

1. In the upper-right corner of your screen, select Find.
2. In the Find window, type T4, select it from the list and click Go.
3. On the T4 - Summary page, select Enter New T4.
4. Enter your amounts and select Done with T4.

If you are having trouble finding the return you want to change, please make sure you are logging in using the right account. https://turbotax.community.intuit.ca/replies/2648026