Get 2nd Value in Dataset in Reporting Services

This seems to be a very simple question, but I am trying to get the 2nd value in a dataset to display as a matrix's header value.

In this report, lets say that I have 2 datasets. In Dataset1, I have a query that pulls down 3 values for a parameter dropdown selection. In Dataset2, I return a result set and have bound it to my matrix.

Within the matrix, I have my repeating columns, and then 3 additional grouped columns to the right that have aggrigate values that I want to display. On the header of those 3 columns, I want to display the 3 values displayed in my Parameters dataset. Within the context of the matrix (and its dataset), I can get the first and last values of a different dataset (Dataset1 in this case) by using:

=First(Fields!DateDisplay.Value, "Dataset1")
=Last(Fields!DateDisplay.Value, "Dataset1")

I need to get something like:

=Second(Fields!DateDisplay.Value, "Dataset1")

How do I pull this off without violating the scoping rules on aggregate columns?