You can install the Craftforge JQL functions
https://plugins.atlassian.com/plugin/details/31601
You then create a filter
project = MyProject AND fixVersion = “1.1.1” and issuetype in standardIssueTypes() and status != Closed
Call this filter for example ‘parentIssues’
Using the JQL
issue in subtaskIssuesFromFilter(“parentIssues”)
will retrieve all relevant subtask issues.