Posting Webpages Across Multiple Subsites Responsively

Greetings,

I have three subsites. I have some content one site posted to a page... http://site1.com/content . I want to post the same content to two other pages.. So I want to post the content to http://site2.com/someotherpage and a third site http://site3.com/someotherpage2.

I don't want to use an iframe because the sites are responsive. Ultimately, I would like to not only post the same content, but also use hierarchy CSS to stylize them for each site.

I was thinking require_once in functions, but its not rendering. Could be something I am doing wrong.

Thanks