They're lovely
I let the kids out to play together for patches of time and keep the mums separate. One of mine, Ellie, is quite bolshy to other goats and yes, she'd bash Rowan and Rowan's kids.
When they go out into the paddocks, the adults are separate and the kids squeeze under the gates anyway to play together
The kids could be 3 months old and in a lot of space (couple of acres) before I let them out all together, and in the byre I won't be doing that at all, the adults will be in their pens.