public class A { IList<B> _listOfB = new List<B>(); public IList<B> ListOfB { get { return _listOfB; } set { _listOfB = value; } } } public class B {}To use the agregation you might do the following from the user class:
A classA = new A(); classA.ListOfB.Add(new B()); classA.ListOfB.Add(new B()); classA.ListOfB.Add(new B()); classA.ListOfB.Add(new B());Best regards,