Even then, you're still only experiencing your own, single, unitary stream of experience, you've just replaced or superimposed parts of it with signals from ano

Even then, you're still only experiencing your own, single, unitary stream of experience, you've just replaced or superimposed parts of it with signals from another nervous system. But even if you can somehow replace/superimpose the signals coming through their optic nerve, for example, into your own experience, that still doesn't answer the question of whether or not they have their own stream of experience to begin with. That is simply unknowable, outside of the reasonable assumptions we all make to avoid solipsism (but they are still assumptions at the end of the day).