Will came home first in the LW10/11 to add the giant slalom title to her downhill and super-G gold medals.
The 36-year-old won threee golds and a silver at the Nagano Games four years ago and now has 12 medals in four Winter Games.
Her effort was the highlight of the seventh day of competition.
Elsewhere in the giant slalom Czech Katerina Tepla won the B2/3 category for her second gold of the Games.
American Allison Pearl added a second gpld to her super-G medal to claim the LW12 class.
New Zealander Rachael Battersby took the LW6/8 gold and Austrian Danja Haslacher won the LW2 event.
Nagano gold medallist Eric Villalon repeated the dose in the men's B1/2 event while compatriot secured the B3 title.
The lastest sledge hockey results saw Canada and Sweden draw 1-1, hosts United States thump Estonia 6-1 and Norway beat Japan 2-0.