You may know that WPARs use Name File Systems for creating alternate paths for rootvg file systems. Name File Systems have been around in AIX forever, and when you think about it, they can come in handy when you want to create a second view of a subdirectory. A Name File System is a pseudo-file system - a way of making a subdirectory its own dedicated mount with its own mount attributes such as cio, read-only etc.
Even if you don't use Name File Systems for that, here are some ideas of where an alternate path can be helpful. This is from my PowerITPro article on Name File Systems published on PowerITPro.
You can read the whole article on Name File Systems here. It also shows how you can do a file-over-file mount.