Can't add child of constraint as a parent

Hi riverg,
thank you very much for your support request.

First of, a quick intro to the child of constraint because you mentioned having a hard time getting the grasp of it:

Imagine you have a magazine in a gun. The hierarchy of your model would look something like this:

Right Hand

|  | - Gun

|      | - Magazine
Left Hand

So by default, the magazine is a child of the gun. But during reloading, you might want the magazine to temporarily become a child of the left hand.

In that case you would add a child-of constraint to the magazine (in config mode). During your reload animation, when the left hand grabs the magazine, you would change the "parent" property of the magazine to "left hand". From that moment on, the magazine follows the left hands movement as it virtually alters the hierarchy to this:

Right Hand

|   | - Gun
Left Hand

    | - Magazine

---------------

Now to your Problem: Staying in the example above, you would get this error message if you would for example have the child-of constraint assigned to the right hand and then you would select the "magazine" as parent for the right hand. That would create this hierarchy and this is not allowed/supported:

Magazine

| - Right Hand

|   | - Gun
| - Left Hand

That would give you this error message you mentioned.

If you share some details about what you are trying to do, I can give you more tailored instruction

I hope this sheds some light. Let me know in case you have any follow-up questions.

Best regards,
Peter