Of course you can reuse symbols with different part numbers in DxDesigner. You will want to have DxDataBook to allow searching, instantiation and verification of parametric data (part number, value, tolerance, etc). Otherwise you will need to manually apply the part number and properties to map the generic symbol to the part, which is defined in PADS.
With the Expedition Enterprise flow, there is a Part object that provides the detailed logical/physical mapping of symbols and cells, those are created and edited in the Library Manager application.
The PADS forum (Desktop PCB Design) may be a better place to discuss library management in the DxDesigner/PADS flow.
Reusing DxDesigner Symbols has been a feature for some time. But like a Land Pattern, the symbol isn't where reuse occurs.
Our Pads Suites for engineers now include DxDatabook which allows part information to be entered in a table to reuse a generic physical symbol.
The DxDesigner for Expedtion utilizes either the Central Libary alone or in conjuction with DxDatabook or DMS and maps the Part information to symbols and Cells.
DxDatabook assists in searching for, selecting, verifying, updating, and changing parts quickly and accurately on your schematic.
Check out how it works in our on demand multimedia!
Gary Lameris, Technical Marketing Engineer DxDesigner