I might be missing something basic but here is what is going on:
1. From Site Admin->Themes I activated BuddyPress Social Child and disabled all other themes for now
2. From Appearance->Themes I selected BuddyPress Social Child
3. Under bp-social-child folder I created top-bar.php and pasted the content from bp-social folder
4. I made basic modification by changing "Welcome back" string
When i visit the page, the parent content is displayed and not the child. if i modify the parent, it works fine. If i modify the child, modifications changed.
One thing I noticed in my setup however is that I have both parent and child under themes\bp-social\ folder but not sure if that would be the cause if it is rendering correctly