Updates:
My uncle passed me 5 juvenile 7" crossbacks, on 28 May with comm damage (split fins, scales missing, head scratched up real bad, chipped scales etc.), commed it together with the peaceful giant.
Second week now and all seems good. Big fella didn't show any signs of aggression. The smaller aros have now "stabilised" (still a little skittish in the tank) but are still fighting among themselves.
Hope to groom them into their full potential and let's see what development goes on for them.
Cheers!