Challenge 3: One Slicer Controlling Two PivotTables — Solution Walkthrough

Setup steps:
  1. Click into either PivotTable (e.g. the one summarizing Sales by
     Category).
  2. Insert > Slicer, tick "Category," click OK. A Slicer panel of
     clickable category buttons appears.
  3. Right-click the Slicer, choose Report Connections (sometimes
     labelled "PivotTable Connections").
  4. In the dialog, tick BOTH PivotTables — the Sales-by-Category one
     AND the Sales-by-Region one — then click OK.

Result: clicking any category button on the Slicer now filters both
PivotTables simultaneously to that category, even though the second
PivotTable doesn't even display a Category field anywhere in its own
Rows/Columns/Values layout.

Why a plain Filters-area dropdown on just one PivotTable can't do this:

Excel Fundamentals Chapter 9's Filters area is a property of ONE
specific PivotTable — a field dragged into that PivotTable's own
Filters box only ever affects that single PivotTable's own display.
There is no built-in mechanism for a Filters-area dropdown to reach
across and also filter a completely separate PivotTable, even one
built from the exact same source Transactions table. A Slicer, by
contrast, is a standalone object that ANY number of PivotTables can
be explicitly connected to via Report Connections — it isn't owned by
a single PivotTable the way the Filters area is, which is precisely
why it can broadcast one filtering action to several PivotTables (and
any PivotCharts built from them) at once.

Notes:
- Both PivotTables must be built from data that actually contains a
  "Category" field somewhere for the connection to make sense — if
  the Region-based PivotTable's source data had no Category column
  at all, connecting the same Category Slicer to it wouldn't have
  anything meaningful to filter by.