Thank you to the user who submitted a Google Form last month! "John" had already been added to the index (both inputs and outputs), but the closest female equivalents of the name are "Joan" (♀), "Jane" (♀), "Jen" (♀), "Jean" (⚧), or "Janine" (♀). I've added "Nigel" to inputs and outputs, and the female name counterpart is "Nigella"/"Nigela" (♀), though far from a common name. (cont. in comments)