How to update manufacturing calendar from 4 to 5 days

Summary:

The plant was originally set up with a 4-day work week. It has been running on it for about 6 months. It has been requested to change it to 5 5-day work week.

Content (please ensure you mask any confidential information):

The plant was originally set up with a 4-day work week. It has been running on it for about 6 months. It has been requested to change it to 5-day work week.

What is the correct way to go about doing this? Last time I tried updating a work week calendar, we had problems, so I want to do it correctly this time.