How to change split orientation of 2 of 3 panes in vim?

Question

It's clear how I would go about changing the orientation from a vertical split to horizontal with 2 panes, but I'm curious if it's possible to do it when I have 3 or more panes. Consider the following window setup:

+-----------------+
|Nerd |   |   |   |
|Tree | 1 | 2 | 3 |
|     |   |   |   |
+-----------------+

So, in this setup, you can see I'm focused on 3 vertically split panes. However, I would like to "rotate" 2 and 3 to use a horizontal split instead, thus resulting in something like the following:

+-----------------+
|Nerd |     |  2  |
|Tree |  1  |-----|
|     |     |  3  |
+-----------------+

Is something like this possible?

Answer 1

1. focus 2 then :hide
2. focus 3 then :sp 2 (2 here should be filename, or :sb (2's buf number) )

demo:

Answer 2

In each window, CTRL-W J will move it to a horizontally split window at the bottom. Then CTRL-W H on the NERD Tree window to move it vertical left.

I have not found a better way, unfortunately. This method scales very poorly.