I use JQL Tricks to return all issues that have a certain link type. That query is:
issue in parent("issue in linkedAllIssues(CH-58,\"contains the scope\")") OR issue in linkedAllIssues(CH-58, "contains the scope") OR issuekey = CH-58
This returns the issues that have a link type "contains the scope" with CH-58 (CH stands for "charter" by the way).
Unfortunately, it does not get deeper than the epic. So, for example, if it returns epic SF-99, SF-100, and SF-101, it does not return the issues and subtasks belonging to those epics.
Basically, in addition to what is already being returned by the JQL above, I need the JQL to also return any issue and subtasks whose epic link “is scope within” the selected charter.