Is she using thin socks?
I like these but people have their favorites. If they are much thicker than a pair of nylons, she'll have issues (and cold feet).
https://www.wigwam.com/products/p-whisper-socks.aspx?productid=2387
From realskiers:
"Socks play an insignificant role in providing insulation, a job better left to the inner boot. The role of the ski sock is to be slick, the better to slide into a recalcitrant boot, and to wick, as in moving moisture away from the foot. Using a thicker sock to boost insulating properties is an enterprise doomed to failure.
The thick sock — or, worse yet, the dread double-sock — takes up every iota of space that ought to be reserved for the miniscule amount of trapped air that’s essential for insulation of any kind to be effective.
It’s also more prone to wrinkle, sag and bunch, none of which is good. Not to mention that it’s probably made from the wrong fabrics, piling on more demerits. Worst of all, thick socks compromise circulation in the foot, resulting in cold feet at best and possibly even frostbite.
If you’re using thick socks to fill up excess space inside your boots, Lord help you.
If you want warm feet, buy an ultra lightweight synthetic blend ski sock. Make sure your boots are warm when you put them on."
