On 21/10/23 10:49, Mauro Aranda wrote:
 > On 21/10/23 09:45, Eli Zaretskii wrote:
 >  >> Cc: Juri Linkov <juri@linkov.net>
 >  >> Date: Sat, 21 Oct 2023 09:16:28 -0300
 >  >> From: Mauro Aranda <maurooaranda@gmail.com>
 >  >>
 >  >> +Since both @file{.dir-locals.el} and @file{.dir-locals-2.el} file
 >  >> +might exist in the same directory, there may be some clash about 
which
 >  >> +file you want to modify when executing the above three commands.  To
 >  >> +solve that, all three of them take a prefix argument, to indicate
 >  >> +which file you want to modify.  When both files exist, a prefix
 >  >> +argument means to prefer to modify @file{.dir-locals.el} instead of
 >  >> +@file{.dir-locals-2.el}.  When one of the files doesn't exist, and
 >  >> +you're adding a variable or copying the file-local variables, a 
prefix
 >  >> +argument means to modify (i.e., create) the file that doesn't yet
 >  >> +exist.
 >  >
 >  > I think a better UI is to ask the user when the command is invoked
 >  > with a prefix argument.
 >
 > Yes, that makes sense.  I'll try that approach.

I reworked the patch to implement that UI instead.  Patch attached.