Here's the problem, illustrated.
In my particular case, excess fabric hangs up on my extended calves. In the top photo, you can actually see my calves sticking out.
I also have excess fabric just below the cheek, although with these two pants, since the back crotch point still needs to be extended for my full thighs, some of these wrinkles and folds are for that fitting issue too.
You may have figured out that what you really need is to remove a fisheye-shaped bit of fabric in the problem area. So, you pin it out and all seems well, as shown in this pic.
But now what?? How do you actually transfer that strangely shaped dart to a place where you don't have to sew a seam across your butt?
First, mark the grainline on your pattern/muslin. Next, draw a horizontal line perpendicular to the grainline and below the crotch point. Draw your fisheye dart the width of what you pinned out on your muslin and center it over the horizontal guideline.
Your fisheye dart may be drawn lower than mine; that's perfectly OK. The idea is to pin out the excess where you need it pinned out. The location may lower or higher than my excess.
Next, draw two lines parallel to the center line of the fisheye dart which are each 1/2 the width of the dart away from the center line. In other words, one line crosses the widest part of the fisheye dart at its top point and the other line crosses at its bottom point.
Measure the distance between those last two parallel lines on both the inseam and the outseam. It is important to measure accurately.
If you haven't done so already, trim away the seam allowances.
Next, fold out the dart as one horizontal fold. To do this, make those last two horizontal lines shown in last photo above meet. The inside of this fold is the center line of the fisheye dart.
FYI, the reason the crotch point in this photo is folded over is because folding the dart made the point lay crooked and it was easier for me to just pin it out of the way temporarily since my excess hits right at the crotch point area.
Now for Kenneth King's "magic."
Remember those measurements you noted earlier where the parallel lines crossed the inseam and outseam? Now is when you'll need them.
Extend the waist at the outseam up the same distance as you folded out on the outseam.
Extend the top inseam/crotch point up the same distance as you folded out on the inseam.
True the extensions onto the pattern piece, and voila! You've now removed a fisheye shaped area from your pattern.
Here's my final result. Look ma -- no folds!
Note: Fitting is an ever-evolving process and I've now decided the fisheye dart (FED) is *not* the alteration I need. To read more on about the wedges I used instead, follow this link to my blog entry with the details. This is not to say, though, that the FED isn't what you may need. Read both and compare for yourself, and maybe one of these methods will be helpful to you. — DC.