We have a Jira group that needs to have access to requests. It would be great if we can add a group to the "Request participants" field, instead of having to add each user one by one.

Workaround

The doc below contains a workaround for this Feature Request:
How to add group members as request participants

Many customers previously requested a way to group customers so it's easier for them to view and share each others' requests. The Jira Service Desk (now Jira Service Management) team released 'organizations' in 2017 to address this use case. 

Organizations are groups of customers that you can add to multiple projects. Customers can be members of multiple organizations, and can:

• raise requests in all projects that use the organization.  
• view and search the organization's requests from the My Requests page in the portal.
• receive notifications about the organization's requests.
• share requests with the organization. 

Learn more about organizations by referring to our documentation here.