extending sheet metal flanges

Good afternoon,

First, I would like to thank those of you who have been helping me, you really have advanced my knowledge and capabilities.  I am stuck again, what I have is a tapered sheet metal box and a tapered cover to that I want to socket over the top.  What I need to do is a flange that is perpandicular to the bottom of the body, that extends to the tapered roof, then I want to bend a flange from there, paralled to the tapered roof that is mated.  In the end, the roof and the box will bge spot welded together along the tapered roof.  How do I do that?  Please see attached drawing.

Thank you,

Steve

SolidworksSheet Metal