Overriding default behavior with repeat endings

I am working on a score where I have successfully created a first and second ending. The first ending has a backwards repeat, the second ending does not. I’ve been able to customize those endings so the first one is “1,4” and the second is “2,3”. So far, so good. But I want to create another single ending after the second one with no backward repeat and I can’t seem to do it. Nor can I simply delete the resulting 2nd ending.