You should be able to do so by navigating to an issue and then - in the people section - adding users to the 'Request participants' field, and customers can use 'Add people'. Also, you can CC people if you'd like to add them through email. More details can be found at:
And just as a side note, please remember that you need to have the following configuration enabled:
Badges are a great way to show off community activity, whether you’re a newbie or a Champion.Learn more
Connect with like-minded Atlassian users at free events near you!Find a group
Connect with like-minded Atlassian users at free events near you!
Unfortunately there are no AUG chapters near you at the moment.Start an AUG