How do I created a "softened" corner? 1

Attached is an NX 7.5 model of what I am trying to do. I want to create a corner that fills in the open area with a surface that is tangent to all of the connecting surfaces. Ultimately I want to use this on solid bodies to soften some external corners. I tried to to use the Transition function, but it keeps insists on crossing the connecting bridge curves and nothing changes when use the toggle direction button.

So first, how do I create the needed sheet body and, secondly, what is the best way to accomplish this on a solid body.