Hi Nannyem
I have made these pants for my son in corduroy using flat felled seams – just for the fun of it! When I came to doing the outside legs seams I made sure to topstitch in the same direction (towards the back or front piece) so to keep them uniform. With the pockets I think (from memory) I did the seam flat felled including the pocket seam – weird I know but it worked. For the crotch, I did this after the inner leg seams as I did this as one long seam. Not the way the instructions say to sew the pants just swapped the points around.
Because you have 1/2 inch seam allowances it will give plenty of room to make a nice fold but I would strongly recommend lots of pinning and pressing to make sure you don’t come unstuck – especially at the crotch area as it is likely to be bulkiest. The pocket seam I treated as part of the folding side of the side seam – just make sure you pin right at that area to keep it in place.
Good luck! You’ll find that whatever the way you sew these pants the flat felled seam will provide them with giving more than one wear.
Tamara