User:SOTO/Forum Archive/The Panopticon/@comment-121.45.54.78-20130925110520/@comment-33695797-20191220181239

From Tardis Wiki, the free Doctor Who reference

I think if the character is simply taking the form of someone else, then no, it does not count, even if they use the same actor. It's literally a disguise. We can just write in the plot and references section of the story that they appeared as someone else.

But, if the character whose form is taken on appears with their memories and personalities (like Grace and the Solitract), this is like a manifestation and should count as an appearance.