Awww, I love those colors on her!
I was told once that a sidepull (or a hackamore, for that matter) should sit about two finger widths away from the cheek/jowl bone/area.
Another thing to look for is that soft area right above the nostrils. There's a point on every horse's face where there is skin and very soft cartilage, but no bone. You want the sidepull noseband to be sitting on bone (if it sits in that soft area and you pull to hard, you can cut off most of the horse's oxygen supply...
), not in that soft area.
On Lacey, this is about where I like to have all my bitless options sit. I've played around with it a bit and this is where she responds to it the best while staying out of that soft area:
I think you have it placed pretty well on Miss Flopsy. I might move it a snick farther down her nose, but at that point you might be getting closer than she'll like to that soft area. Play around with it and see what she likes the best. When you find the right spot, everywhere else will feel a little less finessed. :)