You can add or update screens using the debug or by adding blank screens.
Debug mode can help you:
Add a missing screen in the middle or end of a test
Update a screen that has changed
If you create a test and tap record (forth icon from the top), the test will be executed in realtime until the last step. From there any action that you perform will be executed in realtime. Just choose an action from the menu and hit the "Play" icon to execute. If you have a set of actions to perform, add all relevant actions first, then choose "Play".
If the screen was captured a second too soon or if the object tree is partial, click the refresh icon at the bottom of the screen to reload it.
After you are done, edit your test name, add assertions and save.
We highly recommend to change the names of the screens and give them a meaningful name so other members can easily identify them. It will make authoring even easier.
If you want to update a missing screen, just add the screen but don't perform any actions. You can also just add a new screen in debug and rename it afterwards to override the changes.
If you want to add or update a screen or any action in the middle of the test, use the breakpoint to pause the test and transition to recording mode. Every action or screen will be added in realtime.
To cancel the breakpoint just click it.
If your flow is long or you know the resource ID/Text you want to tap on you can just add a black screen, add a tap on resource ID/Text and run the test. 21 will capture the viewport and object tree while the test is being executed.