I'm trying to use your plugin to combine an external RSS feed with the posts for the blog that's hosting it. I appreciate that the plugin uses SimplePie and so can't access the loop of posts directly.
I'm using http://domain.com/feed where the domain.com is that of the site I've installed the plugin on and it says this is an Invalid URL, when I use the W3 Validator is says it's valid, and I've successfully used it in RSS feed readers.
If there's a solution that'd be super. If what I'm looking to do is impossible then it'd be good to know that too.