Shared familys are always exported separately.
Mostely thats oke but for some familys i would like it to be shared in revit (for changing only parts of the family or by using labels to make diferent types) but in the IFC it should be seen as one object.
By making the nested familys shared, thay are always the same in diferent host familys and can all be changesd instantly.
I also think that this saves memory space in revit.
Maby its posible to add this option to the IFCExportAS
IFCExportAS: stays part of host family