So on the dreaming city would that put both Xivu’s arath taken, rivens taken and possibly savathuns brood all in the same spot? Wouldn’t there be infighting lore wise? Or at least a conflict of interest.

The taken respond to the presence of strength, Oryx's taken bowed to other leads they deemed worthy like Malok. The taken may serve many leaders but they are all taken by the power of the deep and it is to the deep that they owe their true allegiance. I hypothesise that if multiple leaders were present the taken would follow the strongest, perhaps we are seeing this in action with the sudden influx of Xivu spawn.

In the books of sorrow it talked about how xivu arath and oryx and savathun would wage war on one another wouldn’t the taken follow that?

That was before Oryx aquired the power to take. They have fought eachother indirectly since Auryx became Oryx but are far too wary of eachothers power to challenge one another.