Just wanted to stick my 2 cents in cause I know people have had success with males being together and its totally possible but I got 2 males that are brothers and were housed together since babies. I got them at 4 months and had them successful together until they were almost a year and then I had to separate due to fights. Probably depends on the chins personalities and all that. It's possible they will be just fine but you might want to think about if one or more fight you may end up having to house one by himself or even all three separately.
Also I have babies that are a 4 weeks old and I was told they should be weaning themselves off mom anywhere from 6-8 weeks of age. I don't know how much it varies from chin to chin but I know at that time I am going to have to make some decisions just like you will. I have to decide between neutering, housing the one male baby solo or see if my oldest male chin (7yrs) will take to him. Gotta be careful to not leave with mom too long, i think 12 weeks is in the gray zone?