With your three males, if they start to fight (which is likely) the best thing is to split them into two groups, leaving the two that get along best together and finding a friend for the single boar. A friend can usually be found from a good rescue through a process known as boar-dating, where you arrange to bring your boar along and the rescue introduces him to several other boars, one at a time, to see if he can find a harmonious companion. The alternative is to have him neutered and placed with a sow (again they would ideally have been 'dated' as not all sows will automatically accept a boar). Neutering must be done at least 6 weeks prior to the meeting with the sow.
The thing to be aware of is the boar-pair may be able to smell the sow and this may result in a few scraps and generally an increase in tension between the two, maybe even a full-blown fight.
It's always lovely to hear from new owners who take on their guinea pigs and want to do the best for them, but it is very annoying that so many pet shops and even some breeders will sell three boars to live together. Because they are social animals and you see quite a few baby boars together when you go to buy it is natural to assume they will continue to get along. Pet shops should warn people, and they often don't. x
There ARE a few members here who are fortunate enough to have trios of harmonious boars. Sadly these are the exceptions and the three boars involved are generally all very easy-going. Sadly there's no magic- trick to get yours to get along, it's luck of compatible personalities, and three tends to be a bad number for boars.
Things you can do to maximise your chances are to have the largest hutch you can get, have three of everything, have more than one hay area, lots of enrichment and places where all three can go to be alone. Space and enrichment are important for helping guinea pigs to get along, but even then there's still a high chance that it won't work as it will still be down to the personalities of all three in the end. Even so, it may be worth giving it a try whilst thinking of a back-up plan for if and when they fall out.