Tammy of Oak Farm Hamstery is the only one I am aware of but I'm not sure she's active any more. The NHC breeder list under the various areas (Northern, Midlands, Southern etc) lists which species each breeder breeds. This is the Midland HC breeder list
MHC Breeders – Midland Hamster Club
Northern HC breeders
https://www.northernhamsterclub.co.u...d=19&Itemid=28
Southern HC breeders
https://www.southernhamsterclub.co.u.../shc-breeders/
Generally though you need to have a wheel and house for each hamster = houses with more than one entrance, no levels or platforms. Any tubes large enough to fit all three in. Scatter feeding could be good rather than 3 food bowls. When taking them out to handle, best if they are all taken out at the same time - if you take one out and leave two in the cage, the two could get territorial when the other one is put back.
It's a good idea to get advice from breeders. Although it is nice to keep them as groups or trios, even experienced breeders have to separate them sometimes. Once they start getting hormonal at a few months old they can get a bit more prone to falling out. But there are stories of people keeping a pair or trio together for life.
Apart from fighting, other things to look out for is if one seems smaller or one gets much bigger (ie hogging the food).