Hey,
could be possible, that there will be harmony - but it also could be possible that they will start fighting again. Neutering doesn´t change the charakter... And it depends how you put them together and where. Boygroups usually needs some more space then a mixed group. My experiences... Oh, I miss my boygroup "Moritz & Peanut"... they were soo cute together!
But a friend of mine has a big "boy-group" and it works, all boys are neutered.
I think it is not possible to give a 100 % answer if yes or no.
Would be good, if the boys are neutered - anyway. If it doesn´t work, you can give them a girl, of course seperated. And if the partner dies, it is much easier to find a new one, neutered boy and girl usually works...