with arcplan it is no problem to build reports based on different data sources, e.g. Essbase and relational/ODBC.
Drill-through is therefore no problem, just pick up the dimension restrictions from the Essbase view (e.g. Year, Period, Account, Scenario, ....) and query the corresponding lines from a SQL table. If needed you can even put in one screen, Essbase at top, drill-through data at bottom.
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