I am quite aware that you cannot do multiple inherritence by specifying something like this...
public class MyClass : Base01, Base02, Base03
... as in other languages, but it is possible to do a chain of inherritence, which was what I tried to describe using my psudo notation.
Therefore, I have this chain of inherritence, and VS.NET keeps changing the value of the attribute on the aspx page telling which code-behind class to inherrit. I have solved the problem by making the aspx page readonly. It patches the problem, but I guess it doesn't solve it.