Hi! Honestly, best ko na tanungin ang pedia mo directly about combining vitamins kasi depende talaga sa specific brand, ingredients, at kung ano na yung nakukuha ng baby mo from formula or breastmilk, one of my mum friends nag-combine ng two vitamins without asking doctor and the baby had tummy issues, kaya ngayon lagi na kaming nag-check first. Your doctor can tell you exactly which ones are safe together at if baby really needs both or kung isa lang talaga ang kailangan.