Attach file to private message

I am trying to work out the best way to make a file available to max one or two people. Currently as a one off I am creating a temp private group with those people in it > adding a post with an attachment and thus they are notified and can get the file. This does not seem best practice!

I have also tried using private message but cannot find anything in settings that allow attachments and have even tried adding existing file field yo message but get the following error

Fatal error: Call to undefined function privatemsg_check_format_access() in /Users/joethompson/Sites/devdesktop/commons73c/includes/form.inc on line 1944