From the book, 5.1.3 ‘Large scale improvements’:

When large portions of the code is changed the whole team will have to be engaged, and everyone needs to know the goal to be able to help out and understand. The team also has to communicate outside of its immediate vicinity, especially if the change is based on an external goal.

This is the perfect situation for the Mikado Method.

As the code undergoes these changes work is probably spread out over several days, weeks or months, and can benefit a lot from being carried out by several developers on a team. Putting the Mikado Graph on a whiteboard during this period of change is a great way to communicate that goal, the progress and its current state. External stakeholders, managers and other people with interest in the progress are also more likely to get involved if they can see what is happening.