By default, Jira Service Management customers cannot be placed into Jira groups, but you can group them into entities called Organizations.
Customers in the same organization can share issues with others in their Organization (see "Who can customers share requests with?") and see tickets shared with their Organization
If you have several organizations and need management visibility across all organizations, then you need to copy the management team in all organizations.
This is a tedious manual process in case there are several organization groups across several Service Management projects
The VIEW26 Settings allows the configuration of Management Organizations.
This feature allows configuring which organization(s) should see other organizations' tickets.
Refer to App Settings for configuration.