So I've used the hem "Miter Gap" option on flat faces.  As seen lower in this pic:

The problem is there's no function for this if you want to put a hem around the inside of a box lip, as the hems intersect.  I've messed with the hem sketches and done cuts or split lines in the past.  It would just be nice if the hem detected itself and compensated.  I managed to fake a hem, using an edge flange @ 179 degrees with ok success.  It detects the neighboring flange, and trims itself.  Getting the length to be accurate is the trick.  I need the hem feature to do this for me. Any ideas?