How to key frame a clear action parent/child and change pivot point I have two question on how I can key frame them.
I have a scene where a wagon looses two wheels.  The wheels are parented to the wagon.  A driver has been added to the wheels which rotates them as the wagon moves across the scene.

When I get to a spot on the time line, I have the wheels come off and tilt down as they fall.  I could do that without removing the relation ship to the wagon and I do want to preserve this forward movement.


I want to key frame the change of the parent relationship on the Y axis only at frame 814, so the wagon can tilt without tilting the wheels as shown in the picture.
I want to key frame a change in the pivot point of the wagon so it is the left side of the wagon so the left side does not rise up as the right side sinks to the ground.  The current center of the object is shown by the X Z axis in the photo




Wheel connected to wagon
A "Child Of" constraint will let you do what you want, if I've understood your question rightly.
In the constraint settings is a slider for Influence which can be key-framed (by right-clicking in the influence slider and choosing "insert keyframe"). A setting of 0 influence means the child will not follow the parent, and 1 means the parent affects it 100%.  You can have two constraints on the child so it has 2 parents - one with influence set to zero until you need it to take over influencing the child.
This constraint has location, rotation and scale axes which can be keyed by right-clicking in the box and selecting Insert Keyframe.



Edit: where it says "to to" in the picture, it should have said "go to"

Then click on those arrow heads next to there where Add Object Constraint is written, and you'll find the Child Of constraint.