How to add an 'Input Needed' status to reports?

Sometimes our moderators want other moderators to share their opinions. I know there is a status of 'Under Review' but we prefer use that to show a moderator is dealing with it. What we need is also a 'Input Needed' status - so it will encourage other moderators to share their opinions. We've already made improvements to the report center, so you can see the status of each report without having to open it (a simple improvement, maybe a suggestion for IPS?) but cannot work out a way to add another status?