Form changes need to be done individually and not in bulk. Also this requirement itself should be challenged if they are saying all CMDB classes without even giving a list. You should ask the following:
1. Which are the CI classes that they are planning to populate and manage? Only CI classes which are relevant for an organization's business objectives should be in scope.
2. For each of the CI class in scope, you need to understand the form layout changes which are needed. Ideally there should be some variations based on the CI class (As it is very much possible that some key attributes which are important to be displayed on the form for one CI class may not even be available on certain other CI classes)
