node hierarchy question

  1. Yellow is parent node

  2. Red is child of Yellow

  3. Blue is child of Red (not Yellow!)

How to get Blue to it’s position in the picture?

(Red is moved back from Yellow by 1 unit, Yellow is moved left from Yellow by 1 unit and facing it. In other words, Red “sees” the front of Yellow, Blue sees the left side of Yellow).

I think you should set all positions as you wish without parenting and then use wrtReparentTo() instead of reparentTo(). Or use setPos(render, world_pos), setHpr(render, world_hpr).
If I understand the question.

You could reparent it to yellow, orient it appropriately, then use wrtReparentTo(red).

Great idea.