I worked out this family tree for the Plantagenets in Shakespeare’s Richard II. Characters in the play are marked in Amber. You can click on the picture to see it full-size.
The plan is to expand this, one play at a time, until it includes characters from all eight “tetralogy” plays. (Since I’ve already gone back to Henry III, I guess I might as well throw in King John as well.) I’m not sure yet whether this is going to turn out to be a good idea. The final tree might be too cluttered to be useful.