No RSS feeds are available, based on my experience.
There are a couple of ways you can address your issue. You can write some event code to throw a warning in the CME, if content from the parent publication is published, while we have content in the child publications that are published.
You can also create a small GUI extension, that will perform the above, when you right-click on the page or component. Both will be manual invocations. You can do many things, if we have different use cases.
If a manual operation is not acceptable, you can write a TBB or resolver to also publish out the page (localized or not) from the child publications, if they are already published. This now becomes a different requirement though. If you are using a TBB, you may need additional event code for unpublish requirements.
If you are looking for a feed, you may be better off writing your published page information with the publication details from the parent and child publications to a custom database. You can then run a report or build your own RSS feed page and display it tridion using custom pages. This would need you to re-publish all your pages based on your database design.
You may have to choose what is acceptable (manual vs. automated) and whether this is functionality that an everyday publisher would use vs. an administrator. Hope it helps!