updating facebook page with old blog posts

I’ve installed Facebook plugin. The ‘add new’ post is set up so that it looks like when I do my next blog post it will also post to my facebook page. I haven’t posted yet becasue I would like to update my facebook page with all my previous blog posts. Is that possible? I thought I might be able to go into each post one, ‘edit’ then ‘publish’ and it would simultaneously publish on my facebook page. I’ve tried that but the facebook info now showing on the ‘add new’ posts isn’t showing on the blog posts I’ve already posted. Thanks.