I'm not sure but i think you give it an enchanted golden apple or Notch apple.
If you're in creative mode or you turn on cheat, you can use /time set command to set day and night swapping continuously to fasten the speed of the growth of the baby that is still in your daughter/son 's hand and you cant take it. Once they grew up from a baby you can use both type of golden apples to make them grow(higher) and be an adult. Note: you swap the command many times but dont stop!
Pages in category "If your child has a baby, how does the baby grow?"
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