All three work for me. Though then it would ultimately be the lackey's choice to target her yes?

I don't think they can properly separate from one another. It was shown in the DT that Yoko could take over Shuichi in form but that they couldn't exist outside of the other. And at the end of the series, it was sort of explained how Yoko was content with living within Shuichi and that the arrangement suited them both. So I think it's either one or the other, not both, since I think they both use the same life energy.