Incoming RSS feed to create new posts

Hi there.
I’d like to build a site whereby members can add their RSS URL to a field as part of a membership form on my site.

From then on, each post the member creates on their site, their RSS feed creates a post in a specific category (they select) on my site.

There should be no limits of the number of RSS feeds allowed.

I have the membership/category part sorted. It’s the RSS feed I’m stuck on.

Please, any ideas on a plugin that could perform this task?

Thanks.