Well, one way of understanding the relationship is this: krav maga, "looks like kenpo," because kenpo offers a general theory of martial arts, so that styles such as km are special solutions (and I mean this in the sense of "general," vs. "special," relativity) of the larger system.
In other words, krav maga may represent a perfectly-valid, but restricted, set of techniques--kenpo would be the general field from which styles such as km can be drawn.
This does not at all imply that Mr. Parker invented krav maga, any more than Darwin invented sharks.
And before anybody whomps it up, let me be clear about something else: this does not at all imply that I am capable of beating up everybody who studies km because, "I know kenpo." In the first place, kenpo and I have barely met; in the second, of course there are folks in every style there is fully capable of having the likes of me for lunch.
Let me put it another way: I suspect that Mr. Parker was quite capable of fully understanding anything and anybody he might've seen in krav maga, and I strongly suspect that the opposite is not even close to true.