From SuspireWiki

(v., informal) To use familial connections and obligations for political ends; to abuse personal relationships for political gain; to crassly invoke personal, especially familial, relationships in a formal situation. The image meant to be evoked by this word is that of the petulant young prince demanding attention or afection in the midst of a meeting of statesmen. A modern mockery of a jacking vampire typically begins by whining something like, “But Mummy, I want to…,” or, “Please, sire, can’t I have…,” like a spoiled rich girl.

Did you see him mumming for feeding rights when the Regent was standing right there?