Ihor Radchenko <yantar92@posteo.net> writes:

> What about the approach we already use in
> `org-attach-id-to-path-function-list' - check if an attachment directory
> already exists, generated using any rule, and only if not, create a new?
>
> Similarly, in `org-attach-dir', we can first check local attachment
> directory and return it if it exists. Then, we check attachment
> directory for the symlink source, and return it when it exists.
> If none exists, create attachment locally or relative to the symlink
> source, according to some customization. The default will be creating
> locally, to follow the existing behavior.

See the attached tentative patch.