I'm very interesting in begin able to filter the children shown under a portfolio item, e.g. I have a number of teams (assigned to their own projects) that are working on shared features and epics. As a result the features and epics are assigned to a parent project. Using the Custom List App I've been able to create a view that shows only epics and features under which a specific team has stories, but when the epic/feature is expanded it always shows ALL the other features and stories. I'd like to be able to view ONLY those features and stories assigned to a specific team. It appears that filters on the portfolio view only apply to whatever portfolio items is being viewed, in my case the epic. You can create more advanced filtering to filter the epics based on attributes of their children, but I cannot figure out how to actually apply a filter to the children being show.
Here's an example. Using the Custom List App I added the following query: (Children.Project.Name = "Octants - DDC")
I have my global project set to "Advertising & Social - DDC". The results displayed are one epic with four features:

Note that my query is working because it is showing only the one epic that contains a feature (child) assigned to the project "Octants - DDC". What I would like to see instead is only the one feature shown below the parent epic. Ideally I'd like this filtering to populate down to the story level as well, so that if e.g. F5464 assigned to "Commitbit - DDC" contains a User Story assigned to "Octants - DDC", then I would see both F5480 and F5464, but when I expanded F5464 I would see ONLY User Stories assigned to "Octants - DDC" and not any assigned to other projects.
Please let me know if this explanation makes sense. I'm happy to elaborate if someone has any ideas how this could be accomplished. I think there is a lot of potential value for my teams in being able to view their work this way. It creates a way for them to view their work from the Portfolio perspective, but without the clutter of features and stories that don't concern them.