Well, not exacly. You can add a group compossed by a single very small triangle, though. The idea would be to use the "Add part to the bone" button to add an irrelevant model and the collapse it to a single p file when saving.
There is an easier way of removing blinking, though, that consist simply in adding an irrelevant model at the begining of the models list for the head bone (in the HRC file).
I've seen someone befor use a more elegant method that consisted in adding a pair of poligons right in front of the eyes textured with open version of the eyes and left the inderlying model with the eyes closed. That way blinking actually worked.
It was specualted that one could actually go as far as adding more frames to this blinking animation, but such thing should be done manipulating field scripts.