Umbraco 7.2 Forms (not Contour) - Record Action other than Approve and Delete

I'm developing a charity website where families apply for grants for children with rare diseases using Umbraco Forms. What I need to do is send a custom email back to the family when a Grant Application is approved and a different email when a Grant Application is disapproved.

I'm using UmbracoForms.Package.4.0.1 with Umbraco 7.2.1 and I require to add a new state to the form called Disapprove. So that in the form entries page the user will be able to Approve, Disapprove or Delete a form.

How can I append the state Disapprove to the form states?

Many Thanks,

Gus