Can someone in a junior/lesser PU with Burgundy inherit them?

Looking at Europe, I came across a suddenly large Brabant. At first I was impressed, but then I looked at the timeline and saw that it was all the Burgundian Inheritance.

Does it mean that Brabant can inherit Burgundy while under a PU? I'm not sure what happened here.

Screenshot 1475 May.
Screenshot 1476 February.
Bonus : 1500.