I am building a summary calculation sheet based on pivot table data.

In order to get a YTD range, I am attempting to use:

=SUM(OFFSET('Trended Detail'!AR138,0,,,3)) - for the YTD total for the
first 3 months of the year.

What I would like to do is use GETPIVOTDATA to extract the cell address of
the first month's subtotal cell. This would allow the pivot table to be
drilled and/or changed without altering the summary sheet.

Is this possible? Is there a better approach?

Thank you for your help.