How To Put New Data Into SqlDataSource Update With Concatenated Key?

Here is the problem.

I have table such as this

PK selection VARCHAR
PK selection_choice VARCHAR
      show BIT

When I use the sqlDataSource to create an update it creates this.
UPDATE lu_selection_choices SET show = @show WHERE (selection = @selection) AND (selection_choice = @selection_choice)

Now this is OK, but when you perform an update and in say a details control you change the selection_choice the value of the parameter @selection_choice is going to be equal to the old data.  So it performs a successful update on show which isn't being changed selection_choice is.

So the questions is.  Is there anyway to tell the update function of the datasource to insert the a new parameter with the SET selection_choice = @SOME NEW PARAM slection_choice?

Thanks,

Darren King