This is video is a small example of the various ways to add a finger lock to other common joint locks. This is known as Yubi Jime Waza such as in Yubi Jime Note Gaeshi, Yubi Jime Shiho Nage, Yubi Jime Tekagami, Yubi Jime Sankajo and Nikajo Tsukami. There are many others and these are but a few samples of ideas.