Neutered boar or baby sow?

[Alicia]

I have 3 sows, and once I've got their new hutch next year I'd like to get another guinea-pig, because on here I've read that even numbers are better so none of them are left out (and I've noticed Sasha does seem to be left out a bit) but when I introduced Sasha to Edie and Marmalade earlier this year, they all started fighting. Edie and Marmalade attacked Sasha, then Edie attacked Sasha and Marmalade attacked Edie so it really unsettled all of them. Fortunately since then they've got on fine, and there hasn't been any fights since but I'm very worried about this happening again, so I don't think I could really get another adult sow.
I know it depends on personality but do you think a baby sow or a neutered boar would be less likely to unsettle the group as much as last time?

 

[Connie]

I think it all depends on the group dynamic. They could reject either, you just have to introduce propperly and carefully, then hope for the best!