You can use multiple parent-objects to define the position of an object constrained with the Parent/Child constraint.
To create an offset with multiple parents:
- Expand the constraints folder in the Asset browser and select the Parent/Child constraint.
- In the Properties window, expand Constraint Source Weight.
- Set the Translation, Rotation, and Scaling offsets for the Parent object you want to affect.
- Do this for all the parent objects you want to change.
You can key and animate this offset by activating the Key and Animate buttons next to each setting you modify.