Before undertaking the change, one should explore the problem statement, place of implementation, and solution approach from the end-to-end supply chain viewpoint.
The design approach, including the ProActive side of changes, configurations, and external systems updates, need to be evaluated and documented before implementation. In addition, parallel rollouts of changes in other systems need to be coordinated and tested before production rollout.
Another important aspect is how the whole customization work will be carried out for different business locations, organizational hierarchy, profiles, environments etc., along with how the changes get moved from one environment to another.
If the vendor company has previously developed enhancements before go-live (call it, existing enhancements) using ProActive architecture, then a thorough regression assessment is mandatory