I really don't think I can follow you.
Each temp-table in the Business Entity Designer has it's own path and does not need to reside in the relative folder of the Business Entity or Dataset. So it's trivial to keep that generic table reused everywhere without duplicating the generation.
And for the class based constructs such as the TableModel, the temp-table has a Package name property - so you can always keep the path the same.
The easiest way to implement this in the Business Entity Designer would be through a plugin. You might use the SmartFrameworkSupportPlugin as a sample. That injects a button in the Ribbon that allows to add some standard fields to the selected table. Likewise you could add a standard table to the current bedgm.
Not sure if that was your problem. If not, please point me to the actual issue