How do you handle grandparents who feed the child differently?

Pick your battles and be specific about which ones matter. Things generally worth holding firm on: no honey under one, no forced feeding, avoiding sugar and packaged snacks as a routine reward, and no food used to stop crying. Things usually worth conceding: an occasional sweet, a different meal timing, portions being slightly larger than you would serve. Frame requests around health advice rather than parenting philosophy, since 'the doctor said' travels better than 'we have decided'. Consistency between the parents matters more than consistency across the whole household.