probably not. it would be easier to block her most likely. what is it that she is doing ?
via email ? on facebook ? what would require an ip ? I think that you might need a lawyer for this more than a computer guy. Even if you could get her Ip it usually doesnt mean much to a judge. She could be doing it from a cyber cafe or a friends cell phone or even if it did point to her house the courts generally dont consider that proof of anything other than somebody in that house did it maybe not her.
But a lot of judges would err on the side of caution and think "well who else would be sending them" and you could get the order. But again this is really more of a legal problem than a computer problem. I can probably show you how to block her from sending them. but for the order of protection you would need legal advice.