Re: Legal issue?
IANAL, but I work for one and I have the 60 odd volumes of Halisbury's laws of England, and the encylopedia of forms and precedents in two bookcases behind me in my office.
Firstly, your not actually "destroying" assets as you can respawn. If you were, then taking the argument to it's logical conclusion anybody participating in a game would be causing criminal damage.
As so far as I know there is no law anywhere in the laws of England that would specifically prohibit somebody from hiring somebody to spawn kill somebody persistantly, although a search suggests that the "Protection from Harassment Act 1997" could be potentially applicable due to it's extremely vague wording on what harrassement constitutes, should one wish to bring a private conviction.
I will note that the chances of getting the court case accepted into an English court are negligable, since spurious prosecutions tend to attract the wrath of judges for bringing the law into disrepute. Even if the case did go ahead, you'd have to persuade a jury that daddy was harrassing you while you were maintaining good enough relations with him to be able to live in his house.
Good luck with that!