The way developers test Blink/Webkit still (they just test one browser in the family, be it Chrome or Safari largely depending on the web developer's home hardware) it's hard to consider it a hard enough fork to count as two separate engines. Sure, reality shows more divergence than such web developers that test that way tend to generally expect/believe (Safari as Apple-only "LTS" Chrome), but that perception and its reflection in testing alone seems reason to consider the family together (especially with Edge moving into the "family" for among other reasons that very reason of "simplifying web developer testing requirements").