Andrew Silke covers constraints for animators with this look into working with referenced rigs in Maya.
Bringing in rigs as a reference in Maya is standard practice. While referencing offers a fantastic way to work within a pipeline flexibly, things like simple parenting can go out the window. Watch this short tutorial from Andrew Silk as he covers methods for using constraints to step in where parenting can’t.
Constraints can offer a solution to parenting for animators, and In this example, Silke shows how to parent a wrist control to a waist using constraint fundamentals.