[Koha] Serials Planning Help

I have a strange Serial planning question. American Libraries publishes 6 issue a year, and number them like this: Volume 42 #7/8 Volume 42 #9/10 Volume 42 #11/12 Can anyone come up with a way to enter this in to Koha to allow for this type of numbering? All I can come up with (and it's way sloppy) is to tell Koha that it's 12 issues a year and then delete every other issue and manually edit the volume/number field to show 7/8 or 9/10 etc. Thanks in advance for any tips you can provide. Nicole PS. I am still looking for serials planning examples from all types of journals/magazines so that I can share them in the manual and save new Koha librarians time!