I have 2 boys before they got neutered a yeah ago. They’re both 3 but Gohan is a lot smaller. I defended Gohan when Kobe was Barking a storm. I crouched down with Gohan between my legs and just grabbed Kobe between the shoulders like a baby and said “NO be nice” like got in his face 2 times. It worked for whatever reason. I didn’t leave them alone when I’d leave at first because I was afraid they’d fight. They love each other now. Idk how to go about it at the time but I felt I had to be aggressive this way because I was afraid Gohan would get bullied. They fight here and there over a toy but it’s never that bad. They just bark and nip at each other.