JQL-search for sub-tasks in a parent tasks having all other sub-tasks closed

[Anuj Bandyopadhyay]

Hi - 
Here's my scenario: I need a filter to return ALL stories that are IN PROGRESS AND a certain sub-task underneath is completed AND another sub-task not completed.

Example: Give me a list of all stories (like Story ABC below) that have DEV & QA subtasks closed but DEMO is NOT CLOSED.

Story ABC
[
Subtask 1 titled "DEV" - CLOSED
Subtask 2 titled "QA" - CLOSED
Subtask 3 titled "DEMO" - TO DO/IN PROGRESS
]

Can issuefunction() help in this instance?

Thanks in advance!!