My fiance's sister is being stalked/harrased by a potentially violent kid

Well, good, the question becomes, does he go back to Africa on two feet or in a box? Good work, the cops know the idiot and they know that you will use force to defend the family if needed. So they will not be surprised if they get a call that you had to center-mass his ass.
So restraining order is good to get the ball rolling if he comes near the house. The call should go "I have a restraining order against Mutumba here and he's acting strange, i think he might get violent, iif he tries to get into my house I will use deadly force to defend me and my family, you have a copy of the order on file, get your asses over here right now!"
See? You have given all the pertinent info quickly AND help to clear yourself in case you have to shoot him.

Now the key is, IF you have to use force, you MUST do so in a manner that makes it look legal, chasing him down the street with a snub-nose 357 and putting hollow-points in his back is not legal. Putting three in his chest because he kicked in the front door with a knife in his hand is. The bigger the knife, the better and not one from your mother-in-law's kitchen set and make sure that only his prints are on it. because this turd has a record and because he's already a felon and because you already got an RO and you told them in person, they will want to help you clear this shooting, the way they see it is that you did them and the rest of society and the US government a huge favor.

You set the table, let's see if the asshole comes to get some.

 

Rich's advice here is absolutelygaddamntrue, if this goes down, make no statements without and attorney present.

 

But not according to this:

Mutumba?? Where dahell'd ya get Mutumba?

 

The name just came to me, IDK why

 

...somebody watches too much law & order...

 

Just thought I'd clear some stuff up about California self defense and murder vs misdemeanor.