Writing Another Person’s Memoir: Can you use the first person pronoun?

Shouldn’t writing another person’s memoir be called writing biography rather than writing memoir? You the writer are, after all, not the subject. Doesn’t that make it a biography?

But, are there occasions when a biography can justly be called a memoir?

In one of my books, A Sugary Frosting / Life in a 1960s Parsonage, I used lifestories that my late wife Martha Blowen had composed—and to which I added text. And…

I called the finished book a memoir.

Was this appropriate?...