why do you even need to create a uworld?
why not sublevels, dynamic streaming levels, datalayers, or levels?
i think you should start by explaining why are you trying to do this.
handling worlds this way is very weird. and very likely you don’t need it. and very likely it won’t replicate.
you don’t need different viewports. you just need to change the camera.
if you want players not to see each other you need to use netrelevancy.