MAke sure that the datagrid in the middle has the option select first set to true, then changing the selection on the left will refresh the middle one and because the first row in the middel datagrid is selected this will refresh the one on the right.
Hope this helps you further.
When using the following domain model:
and a page like below with the grids displaying the information by xpath and the grid on the left and middle have select first set to true this will refresh the level 2,3 and 4 by selecting one of the level 1 items when your page is setup like below:
SO it might be that you need to have a look at your setup of the page or your datamodel is somehow different.