As an app developer, you can define multiple glance modules in your descriptor, but Jira will only display the first glance module returned (after any conditions have been evaluated). We recommend you avoid selecting conditions that result in more than one glance appearing on an issue.
If your app has multiple entities you want to represent using glances, you can make use of conditions. For example, if you're building a Git integration, you might want to show related commits, branches, and pull requests for an issue.
In this example, you could define a glance module in your descriptor for each of these:
For each glance you could use a predefined condition, like entity_property_equal_to. You could then define the condition to decide which glance to display.
Your app may want to have an experience where you want users to take an action before you display a glance. You can define multiple glances to create this experience.
When a user clicks your glance, you could use the modal dialog target to design a view where the user links a conversation to the issue through your app.