C# Inheritance and typeof - .Net 2.0

Question

Good day.
I am developing a .Net 2.0 application using C#.  My problem is this: I have a class named Record() and a derived class named Message().  From Message() I have multiple derived classes (BaseMessage(), Struct(), etc.).
I have a folder container object that retains a list of objects and this container object has an attribute AllowableContents:
   [AllowableContents(new Type[] { typeof(Record) })]
When I execute my app and right-click the container object, the drop-down list contains my Record() class and all derived classes (Message, BaseMessage, Struct, etc.).  I only need to see the Record class listed - can this be done? 
I appreciate any assistance in this - thank you.
- Lawrence Tsosie