WordPress.com does not provide any tools for autofilled content of posts and pages as those tools are the tools sploggers who steal blog content use.
see: types of blogs allowed and not allowed
If your professional blog has an RSS feed then you can place an RSS widget in your sidebar of your free hosted WordPress.com blog. The RSS Widget displays posts from any RSS feed. You might find this handy if you want to show off one of your other blogs, or one of your favorite blogs, in your sidebar.