We took a short look and it does not look easy to implement. Also not many other software packages support this and even something like Beyond Compare does not seem to have a 3-way compare. This may be something that we can look at eventually but it will probably be a number of years before we look at it seriously as we have a lot of requests for features that we are working on now.
Currently the only ones with more then one compare are programs that are memory editors like cheat engine and so on
They allow you set the types of compare that would be present in the next like greater then last of = to first and all that fun stuff…