This is already an option for Stakeholders, and should be for Key People too.
Yeah. That's pretty strange. I just looked it up in the old app to see if we missed it, but it's not in there either. Definitely a great suggestion.
I'm going to mark this as Deferred, since it wasn't in the old app either. But we will definitely come back to look at this. It shouldn't be too difficult to add optional contact fields.