If you select multiple attachments in the view port and try to parent them to a bone using the hotkey, the slots will be duplicated but the attachments won't. The original slots will have a missing attachment so you cannot call it a complete duplication. If you filter the tree view by slots, clicking on the attachments in view port will select the associated slots. By using this filtering, you will be able to parent multiple slots to a bone without the awkward duplicating slot but not the attachment behavior.

Updated face keyframe and some weights.

Two bone IK constraints and weight fine-tuning.

Added more weighted bones for less clunkiness.

Rigging/weighting to compensate for curved fox tail art.