I think it is possible to use both Sam and sharon in Cap 2, just have them be SHIELD agents.
Sharon's an up-incoming shield Agent who thinks this assignment could be a big break but found out she is being played by Fury.
Sam's a researcher/rookie agent who becomes cap's friend and Cap tries to train him for field work. He is a researcher working on glider tech but he has a special gift, the bird whispering thing he does so he tried to become a field asset a la pym. He fulfills the Rick jones role of someone trying to get Cap acquainted into the real world.