To add someone later on private story on Snapchat, follow these simple steps:

1. Open the Snapchat app on your device.

2. Tap on the Profile Bimoji in the top left corner of your screen.

3. Scroll down and press the View More option.

4. Locate the private story you created and tap and hold it.

5. Next, choose the Edit Viewers option.

6. Select all the friends you want to add.

7. Now, hit the Save button.

For more info read here: https://allinsider.net/w...e-lock-mean-on-snapchat/