how to find or query on a field from multiple feature classes

I just started using the flex viewer. previously I used the ArcGIS server manager app builder and could create a find or query that used the same number ID field from three FCs of different geometry (point, line, polygon).
I only seem to be able to pick one FC for an attribute search. the query widget specifies that it can only be used on one layer, so i was hoping the find widget would have the ability to use more than one FC.
Thanks,

Steve