public class MyBase {

  public List<SomeObject> list;

  public MyBase(){
    list = new List<SomeObject>();
    list.Add(new SomeObject());
    list.Add(new SomeObject());
    list.Add(new SomeObject());
  }

  ~MyBase() {
    foreach (SomeObject obj in list) {
      obj.Cleanup();
    }
    list.Clear();
  }

}

public class MyDerived : MyBase {

  public MyDerived() {
    foreach (SomeObject obj in list) {
      obj.SomeProperty = new Handler();
    }
  }

  ~MyDerived(){
    foreach (SomeObject obj in list) {
      obj.SomeProperty.Cleanup();
    }
  }

}