|To help myself, I took pictures of my fly front construction based on the hot patterns instructions. Once you get the hang of it, it's a simple and nice way to install your zipper.
pics and instructions here
Debbie Cook looked at my pics and noted that perhaps I had done the last few steps wrong. I had originally emailed the page to Trudy to get her take and she didn't notice the "wrongness" so thanks Debbie for the sharp eyes.
The rectangular fly piece should actually lay over the shaped fly piece and be held in place by an extended part of the waistband.
Here is Trudy's further explanation to me:
Hi Jennifer, thanks for your mail.
Re the pants fly & waistband...yes, they have a similar construction to a RTW menswear pant, with the waistband extended to seal in the top edge of the fly shield.
Imagine that you are wearing the pants...the shaped fly stitching is visible on the front of the pants, and the finished edge of the front waistband aligns with the finished edge of the fly. If you were to un-do the pants, you would see the fly shield inside the opening, joined to the under wrap of the waistband. it has to be siad though, that there are many different ways to do a front fly, and a lot of it is down to personal preference...
When I have a moment, I will redo the pics.