[FirstYorkie]

Mandimarie - it's hard to tell exactly what is going on without seeing it. It's normal for dogs to play aggressively. Growling and nipping are quite normal. Going for the neck, too, is normal. Does Fiona draw blood when she is playing with other dogs? Are the other dogs yelping and whining? If not, I'm betting that this is just play for them.

If she really is being a "bully", perhaps she needs to learn some manners from a *slightly* larger dog. Be careful, though, you don't want her to get hurt.