Exclude Old Feeds

I have multiple RSS feeds on a page (and your plugin works great). Is there a way to exclude old feeds? For instance, let’s say three feeds, A B and C. The first feed A is from a very active site, B moderately active, and C low activity. While A and B feeds show their latest posts, C continues to show its old feed that can be weeks, or months, old.

To make my page reflect recent content and not look stale, is there a way to exclude feeds by their posted dates? As the C feed becomes stale, it will no longer be displayed on the RSS feed page.

If this can be done, it would help a lot to de-clutter my RSS feed page and make it look more fresh.