Question about young kid behavior. Aggressive 10 week old.

So I've had pet goats for several years. I just picked up two young wethers this week. They're 10 weeks and 12 weeks old and have been slowly introducing them to my 3 year olds. The 12 week old fellow is pretty chill. The 10 week old is the problem. My three year olds of course are keeping them in their place when they're all together. Nothing super concerning, just keeping them out of their spaces, mostly vocal threats and head-shaking and light head butting when they get too close. Normal stuff. The thing is, when they do this to him he will come back and try to retaliate by headbutting them about 50% of the time. Additionally, he's going after the 12 week old sometimes when they're eating together, and because he's big for his age, overpowering him.

I have a bad feeling about this and assume that this is going to probably get worse with time and not better? I'd appreciate some advice from experts.

I know the breeder fairly well and I know she has other wethers available, no doubt she'd let me trade him for another... but I am feeling a bit conflicted. Help?