Line up two objects using child objects within each

I’m trying to line up two objects that each have a ‘mount point’ contained within them. I want the two mount points to line up such that they face each other. I’m struggling to find the correct rotation to line them up. I created a pivot point and added the second object to it, and was able to get the two mount points position to line up, but now I need the rotations to align.

Here is what I have so far:

This is the starting point - the goal is to have the green plane line up with the red plane so that the z-axis of each are reversed, but the y-axis is the same.

Finally figured it out. Was actually very simple:

  • create pivot - move it to the world position / rotation of mount 2
  • attach the second object to the pivot (using attach method - NOT using add)
  • move pivot to mount 1 world position / rotation
  • rotate pivot 180 degrees around x axis
  • rotate pivot 180 degrees around z axis