You can create a relationship between Scenarios and User Stories by linking them, this can be easily completed from the Specifications page.

Choose the Scenario you wish to link to a User Story and click the Issues link to the right, then inside the Issues dialog select the Link existing Issue button.

Begin typing in the Issue field to search across your Jira User Stories, then select the User Story you'd like to link and click the Link button.

​Protip.
​When another user modifies a scenario you will be notified by email, this email will contain who made the change and what has changed.