Have you ever pushed a door open with your shoulder/elbow when you are carrying grocery bags? Well, x2 has a convenient trick like that: When you are drag-n-dropping a selection, hop over to the tree pane, hover on a node and it will automatically expand. Drill down to the desired level and deposit your selection there.
But if you are not carrying anything in your hands, you may as well turn the door handle, no?
Note that you might be also using modifier keys (CTRL, SHFT or both) while you are drag-n-dropping; so no other keys are available.
The only other option is to copy (or cut) the selection first into clipboard, navigate to the desired node and then paste the selection (or its links) there.