A two-hour live action television adaption of Ranma ½ aired on NTV on December 9, 2011. This Ranma ½ special is not listed under season 0 for the Ranma ½ TV show. Currently the Ranma ½ season 0 is locked so I can not add it.
I do recognize that some might say the Live action special is not a direct sequel to the Anime series (one is live action and the other is animated). It was marketed as a "Ranma franchise special". See the advert comparing the anime charters to their live-action counterparts. . .
Furthermore the live action special is not a new series. Recording it as a special under the anime series is the best place for it.