I was doing an internet search for KP images when somehow, an image of this girl sneaked in:
Jen Masterson
She looked interesting, so I clicked on the image to find out who she was.
The background info I got gives her a lot in common with Kim.
I'll summarize:
They're both driven type A personalities with stubborness issues.
They're natural leaders, taking charge easily.
Also drives others to excel, not always in a nice way.
Both are keen snowboarders
Jen plans a future career in this sport.
Also, Jen is quite strong and physically agile.
First attempts at driving ended in disaster.
Jen crashed the school bus and a showroom car, in that order.
Obnoxious younger brothers.
She has two younger stepbrothers, who torment her as often as they can get away with it.
Fashion sense:
Kim and Jen's wardrobes aren't what you'd call traditionally feminine, for which one family member disapproves of.
In Kim's case, she rarely wears dresses, preferring pants or shorts, even if they are specifically tailored for the female form, her Grandmother doesn't like the fact that Kim wears them.
As you can see, Jen wears a skirt, but it's actually a tennis skirt (I assume it's to allow freedom of movement, given her athletic prowess), not a real dress.
They've never said where Jen buys her clothes, but it's suggested she buys them from her place of employment, which happens to be a sporting goods store.
And when Courtney (Jen's older sister) sees her working there, she accuses Jen of "getting a job where she can dress like a boy".
The work uniform is a Referee's shirt.