How do I get the inner railing on my multistory (storey?) stairs to connect at the middle floor levels, but have the proper extensions at the very top and the very bottom? I can't seem to make it work. If I put an extension on the bottom rail, it shows the same extension at every floor level. Ditto with the top extension. I need all the middle floor levels where there are stairs going both up and down, to simply wrap around, like it does at the landing between each floor level.