How much detail is included in the details summary?

Would it be feasible to use conditional expressions to select which dataset values are actually pulled from?

You can specify explicitly the scope (of the Dataset) from which the Fields are pulled by.

You would put a TextBox in your Details section with an expression which indicates which dataset (and scope) to choose from.

Assuming the following:

- You have a parameter named @WhichDataSetParameter which contains the indication to which dataset you'd like to use in the details section.

- You have two datasets that you're choosing from named DataSet1 and DataSet2

Your TextBox expression can be the following:

=Switch

(

@WhichDataSetParameter = "Use Dataset 1",

Sum(Fields!DetailsFirstValueField.Value, "DataSet1"),

@WhichDataSetParameter = "Use Dataset 2",

Sum(Fields!DetailsFirstValueField.Value, "DataSet2")

)