Hi guys! Iâm trying to use GLORP and Iâm having problems defining the class model for a class which has an instance variable which is a collection of instances of two different classes: I have 3 classes named: { Section . Question . QuestionGroup } and I have problems for specifying the glorp class model for Section. Object subclass: #Section instanceVariableNames: âquestions ...' classVariableNames: '' The thing is that #questions instance variable is a collection of Question AND QuestionGroup. They have polymorphic behavior, but they have not a common superclass (besides Object). How does my class model should look like? classModelForSection: aClassModel ... aClassModel newAttributeNamed: #questions collectionOf: ****?. Thanks for the help! Cheers, Alejandro