I need some help trying to make a sheet metal part. 

So I got my sheet metal part with the bend on the bottom flange and it unfolds nicely, but I can not figure out how to add the gusset side sections (shown as the sketched line) that I need. I tired using an edge flange then modifying the sketch but it wouldn't let me do that.  I also tried making a solid and unbending it, but I could select the sides to unfold them.  Anybody know how I can add the sides?

I attached a file (SW 2018) of what I am trying to make as a solid.