I have a JIRA filter which returns all the fixes in a future release:
project = MyProject AND fixVersion = \"1.1.1\" and issuetype in standardIssueTypes() and
There is no need for any Plugin.
Switch to "Advanced" filter option and enter
status in ("Open") AND parent in (PHX-xxx,ENG-xxx)
It will give you all the open tickets present as a subtask in parent JIRAs. Build more complex and enjoy using JIRA. Advanced filter options will also give you all possible values to build Queries.