ADF makes it very easy to create a master detail page with one drag and drop operation from the data control palette onto the page.
But what if you want a master with 2 details on one page?
It's actually quite simple to achieve this - but I got asked this a couple of times last week so here goes...
All you need to do is drag the first detail over and drop it as a master->detail.
Then drag the second detail over and drop it as a table or a form - and now you have the three tables on the page and you are almost done.
But if you'll run your page now you'll find that your second detail is not refreshing when you are switching between the master records the way that your first detail does.
ADF did this synchronization part automatically for the first master-detail you dropped. All you are missing is a partial page rendering setting on your second detail.
See the difference between the two detail tables here:
So let's set it up - all you need to do is go to the form or table that contains your second detail and set its partialTrigger property to point to the master component.
(You can look at the setting for your first detail component and copy them).