Replacing wall plate with load bearing studs
I would pull the window, support the top plate with temp supports floor to plate (cut ½" long and tap the bottoms in until you see a slight  lift in the top plate) cut between the  siding and bad studs with a 12 " metal sawsall blade, remove all wood with any rot or deep fungus and reframe the whole thing. send the  studs through a table saw to make them match the adjoining studs to avoid broken drywall when reinstalling