display-buffer to generate buffer from other window

Question

Every time I invoke vterm, it create a new window below as C :

   +------------+------------+    
   |    A       |     B      | 
   +------------+------------+  
   |            C            |      
   +-------------------------+   

I am aware it invoke display-buffer to act this way.

How could let display-buffer to create a buffer from other window if it exist, rather than generate a third window?

   +------------+------------+    
   |    A       |      C     | 
   +------------+------------+  

Answer 1

You can configure it with display-buffer-alist.

For example:

    (add-to-list 'display-buffer-alist
                 '((lambda (buff-name _) (with-current-buffer buff-name (equal major-mode 'vterm-mode)))
                   (display-buffer-reuse-window display-buffer-in-side-window)
                   (side . bottom)
                   (reusable-frames . visible)
                   (window-height . 0.4)))