It is not often noted (an exception is Hemmenway 1994, p. 265, note 12 [JSTOR]) that the Stranger’s top-most category in his divisions, the “original ancestor” in all his genealogies, is dunamis, power (Sophist 219a4-6). The reason for this neglect is probably that the Stranger does not bring the matter up in his summaries or discuss explicitly the powers that are not forms of knowledge.
Yet in the context of the dialogue, the idea of dunamis as the topmost category in every division makes good sense, since it is also used as an (apparently provisional) definition of being (247d8-e4), and never really retracted; see here Heidegger (1997/1924-25, section 68.b, pp. 328-330) and Dorter (1994, pp. 161-162). All the genealogies or divisions seem meant to begin from the original ancestor of everything, namely being.