In my opinion not only can the mother expect every dirty trick in the book to come her way its likely that every dirty trick that isn't in the book will also be coming her wayThe king giving an illegitimate child a big fat rich feudal hold will set the normal nobility off. Nobility is supposed to be exclusive. The mother can expect every dirty trick in the book to come her way, plus brute-force assassination attempts aimed at her and the child. Her survival instinct will tell her to take a post as Special Member Of The Royal Entourage instead.