@JoeF6497 I imagine the reason you're not able to add screenshots is because you didn't log into your PEGA community account when you entered your question.  You will not have been granted the additoinal features if you're not logged in.  Your profile picture should be visible on the top right of the screen.

Below a GenAI tool answer for your question.  

Based on my research, this issue requires addressing two aspects: case locking strategy and access permissions.

Case Locking Strategy

By default, when a child case is opened, Pega acquires a lock on both the parent and child cases. This is why the Open Work activity is forcing the parent case to open, causing the failure you're experiencing.

To resolve this part of the issue:

1. Open the child case type (B) in Case Designer
2. Navigate to the Settings tab
3. Click on Locking
4. Select the option "Do not lock the parent when the child case is being performed"

This configuration will prevent the system from acquiring a lock on the parent case when users work on the child case.

Access Permissions

Changing the locking strategy alone may not be sufficient. You also need to configure appropriate access permissions:

1. In Dev Studio, navigate to the Access Manager
2. Configure Access Roles that grant necessary permissions for the child case type (B)
3. Ensure these roles do not have read access to the parent case type (A)
4. Assign these Access Roles to the appropriate Access Groups for your end users

For more granular control, you might need to:

1. Create specific Access Roles for working with the child case
2. Configure Access When rules if you need conditional access based on case status or other properties
3. Utilize permission inheritance to customize only the necessary access settings while keeping default configurations intact

Important Considerations

• If you configure a child case to override the locking strategy of the parent case, ensure that the time-out value of the child case is less than that of the parent case
• If the parent case is set to allow multiple users, Pega Platform prohibits case locking configuration on any child case
• Test the configuration thoroughly to ensure users can access and work on the child cases as expected without encountering permission errors

1. Managing concurrent access to a Case - This documentation explains how case locking works in Pega and provides details on configuring locking strategies for parent and child cases.
2. Overriding the locking strategy of a child Case - This reference specifically covers the "Do not lock the parent when the child case is being performed" setting that I mentioned in my email.
3. Case locking - This Academy topic provides comprehensive information about case locking mechanisms in Pega.
4. Application access - This reference covers the fundamentals of access control in Pega applications, which is relevant to configuring appropriate access permissions.
5. Permission inheritance and dependent roles - This source explains how permissions are inherited between related objects, which is important when configuring access to child cases without granting access to parent cases.

These references collectively cover the case locking strategy, access permissions configuration, and the behavior of parent-child case relationships .