Wow! Thank you all for the quick responses. Using a utility class, as suggested by you and
, seems like an intuititive way of handling this problem in the general case, especially if the shared code were to use multiple objects.
After thinking more about the specific application, I realized that there is already "a good fit" for the utility method in ClassThree because all the shared work is just calling a handful of existing instance methods in ClassThree. The new method then becomes a shortcut instance method that calls a number of its own instance methods.