Hello Lehigh Valley Social, 

You may add available in admin panel messenger block to any page and this block will contain private talk for members who can open this page. 

I don't recommend to insert any blocks to main messenger page, because it's height and width are calculated and depend on device and all unnecessary spaces/footer/header are hidden with css and js.  If you add any new block to this page, it may break design and work of the page.