Primary Keys may not be modified
Much of Uniface's internal processing relies on the fact that primary keys do not change. An increasing number of databases do not hold to this "old fashioned" rule. If Uniface's default behaviour is worked around to allow primary keys to change, then difficulties can occur during upgrades (where the functionality is better enforced).
If you wish to change a primary key you can:
No matter which method you use to change a primary key in Uniface, the new value of the primary key will need to be propagated to each of the tables it is related to (as a foreign key). Uniface does not provide any automation for this task.