Actually I really like this idea. Wouldn't quite work for my intergalactic war setting, but it sounds like a great idea. Especially if there needs to be a reveal about family lines, and discovering the family tree is how something is shown.Something like a family tree I'd be wild enough to say just draw it out as a family tree and show it in the book. Blorin son of Blord, son of Blargle son of ..... yeah it might be informative but there are better ways to show it where the info actually sinks in rather than just washes over the reader in a haze.
I've been edging towards something like this with progressive maps, where they're inserted at certain moments after key battles to show how the war is shaping up.