Splitting window displayed in special frame

[Joe]

Hello,

I have set the variable special-display-buffer-names to
  (("*SQL*" (width . 139) ))))
.
Whenever I create a "*SQL*" buffer, it is displayed in a new frame as
it should be.
The only problem is that if something is happening in the mini-buffer
that creates a (temporary) window, like completion, the buffer
*Completions* is displayed in a different frame.
For instance, if I do find-file and press tab to get the file
completions list, it is displayed in another (existing) frame instead
of splitting the window temporary as it is done for other windows.

I tried to set special-display-buffer-names to
  (("*SQL*" (width . 139) (unsplittable . nil))))
but it had no effect.

It should not act different for *Completions* in the special-displayed
buffer from *Completions* of a function issued in a normal buffer.
How can I do that?