extra pin on a part

hi,

     Version: MENTOR EE 7.9.4

     I met a strange situation while I build a part in library manager.

     I want to build some parts for crystals which have different package type. For a crystal, normally it has only two pins on its symbol, so I try to make one general symbol for all crystals with only two pins, and assign this symbol to different packages.

fig.1  crystal symbol with only two pins

                                                                                                 fig.2 package with NC pins                                                                       fig.3 package with gnd pin

    for package in figure 2, I can just assign the unused pin to NC while doing the pin mapping. but for package in figure 3, things get complicated. because the third pin could be connected to a net, some engineer want to  connect it to GND while others connect it to DGND. if I just map this pin to GND in pin mapping dialog, the engineer won't have any chance to change the net name for this pin.

   the question is how to maintain only one general symbol while providing user the opportunity to assign other net name to extra pins other than the ones appeared on symbol?

  thanks