Mommy, sa 4 years old, mas importante talaga ang regular balanced meals nang maraming protein, healthy fats, at carbs, ganyan talaga ang best way to gain weight, hindi lang vitamins lang! Since concerned ka, best ask your pedia kung may specific deficiency ang baby mo or kung anong multivitamin brand ang recommend nila (brands like Enervon Kid o similar are common dito), kasi they'll check kung normal lang growth niya or may need for extra supplements. You're doing a great job being proactive about your child's nutrition, that's what matters most! Keep serving those home-cooked meals with love, and your pedia will guide you on the best next step. Kaya mo yan, Mommy!