A little seasonal crime prevention advice
Now I'll repeat and enlarge upon some of the advice I gave in response to the complaints that the festival is used for aggressive and intimidating behaviour by some. Some of which is tried and tested (By me in person), other stuff I'm familiar with having worked in the byzantine labyrinths of local Government.
First you have to get clever with the bad guys. Not threatening, but making it not worth their while to bother you. Don't want 'trick or treaters' calling? Right, buy the cheapest and least pleasant candy / sweets you can. Don't do anything that puts you in the wrong, but pay lip service only to the tradition and keep your 'guests' at the front door. Get rid of them quickly and don't get into a conversation; nod, smile "One handful only dear. Thank you." Ensuring that word gets around that you have "Crap sweets" should keep the little tinkers at bay for a couple or three years. What you are trying to do here is remove or limit their motivation. Any complaints from them can be dealt with by a cunning "Sorry chaps, you're a bit late - they're all we've got left." Any demands for food, drink, or alcohol should be dealt with by a "This isn't a bank / pub / supermarket you know. Goodnight." and a puzzled expression like you don't know what they want. After all, you'll have done your part - they've had the sweets - the 'bargain' is kept. Speaking for myself, I always answered the door wearing a fright mask and doing my 'hunchback' routine. Never had a problem.
There is another means of dealing with the bad guys, but you need training and more than a little nerve to do it. It is a method I used on every working day when I did foot patrol as a Parking Enforcer. It consists of trying to 'engage' the person who is making the threats, and getting them to behave like a reasonable adult. Without training I wouldn't even try it.
Going further down the line, if you have already had trouble with such 'visitors' and vandalism / threats etc, you can try and get some informal advice on the problem from the local nick. See if they can help. This sort of problem is independent of all festivals, and if you've already been assaulted / had your property vandalised - this is nothing to do with any festival. You are their 'bitch' and the little jokers I'm thinking about love that power. They get off on it. Film them in the act if you can, but make sure they don't see that tell tale red light on the camcorder or webcam. No sense in provoking matters.
Now if you are afraid that going into the local nick might make you a bigger target, then may I suggest this course of action; go to your local Council offices and ask for the Councillor who has the responsibility for the local Police committee. Not a 'Manager' or 'Liaison Officer' who will put you on a spreadsheet and promptly forget about your real problems, but the Councillor who works most closely with the local Police. Bend their ear, politely explain the problem in detail without naming names or pressing charges and make the Councillor's life difficult until a positive solution is found. They want the plaudits and the votes, so make them think that this is a golden opportunity for them to make a 'name' for themselves and get re-elected more easily. If that proves no use, get on to your local MP, in person at their 'surgery' if possible, and try a similar approach. The machinery is there, all you have to do is find at what level the levers of Local Government trip and things start to work in your favour. This will entail taking some time off work, but if you have a problem - You've got to deal with it somehow. As you may have found, there is no short cut.
As for the festival; try getting into the spirit of things. Wangle an invite to a party. Don't be alone. Always remember that with 'aggressive trick or treaters' you are dealing with 'pack psychology'. They prey on the weak because it makes them feel big. It's a low self esteem thing on their part. If your gang is bigger than theirs - they will not bother you so much and you may even be able to relax a little and actually enjoy yourself.
Look, this advice is the best I can offer without details or being there, and I'm not in that line of work any more. Hells bells, I'm not even in the UK any more, and 'Trick or treating' is a bit better organised over here in British Columbia (It's only really for under 11's anyway).
Anyway, I know that it is November 1st now and a bit late for advice on 'Trick or Treat' but best of luck to the afflicted amongst you. I wish you joy and surcease from your troubles; who knows, next year you may even rediscover something you thought was gone forever.