Which design option allows users to modify a shipping address without interrupting the primary case flow?

The option that allows users to modify a shipping address without interrupting the primary case flow is to add a local action to the case type. Local actions are designed specifically for scenarios where users may need to perform tasks that are secondary to the main process without disrupting the overall flow of the case.

When a local action is invoked, users can access additional functionalities—such as editing a shipping address—while the primary case remains in progress. This maintains continuity and allows for a seamless user experience. After completing the local action, the user can easily return to the primary case without losing any context, which is crucial for maintaining workflow efficiency.

In contrast, other options, like adding an optional process or adding a step in the process, would typically alter the main workflow or require a more significant shift in focus from the primary case. Therefore, they do not provide the same level of flexibility and continuity as a local action does.