A method, apparatus, and article of manufacture which provides for synchronizing links and group definitions in an object-oriented system. The method comprises the steps of creating a first class and a second class within a memory of a computer, creating a link between the first class and the second class within the memory of the computer, setting a multiplicity value within the memory of the computer to define a first group within the first class and a second group within the second class, creating an instance of the first class in the memory of the computer where the instance is within the first group, changing the group definition in the memory of the computer to include the instance and link the first group to the second group via the created link, and changing the created link in the memory of the computer to reflect the changes in the defined first group.