Because interfaces expose API names, any change to an interface definition has the potential to break downstream applications and will necessarily break existing object implementations. When adding a new shared property or link type constraint to an interface, all implementations for object types that use the interface must be made in the same update to your Ontology. We also recommend updating your interface definitions and consumers at the same time.
If your downstream applications cannot be updated at the same time as interface changes, you can alternatively create a new version of the interface (as an extension or a standalone interface) and migrate to the new interface definition as soon as possible.