A relative (who is no longer living) wrote a number of autobiographical pieces which I would like to publish in a book. I would like to include four or five chapters written by myself, that would supplement the relative's memories. In addition, some chapters will require a small amount of text written by me, usually at either the beginning or the end of the chapter. By "small," I mean half a page or less.
How do I distinguish between the two voices? I was thinking that for a short bit inside a chapter, I could use italics, or the dreaded footnote. But I don't want to use italics for a whole chapter. I don't want to have to use my first name in the chapter title three or four times. That would be embarrassing. (My chapters mostly come at the end of the book, but there's one that comes in the middle.)