Obviously, at 20 months, there isn't a lot of understanding about these deep concepts. To introduce Brookie into the whole "Mommy had her baby thing," they had the rest of the family wait outside so Brookie could meet her brother by herself. The rest of the family eventually trickled in to hear Brookie's excited monologue.
Jana referred to Brayden as "your baby" and Brookie took that seriously. She didn't even want her Mommy to hold the baby to nurse him. It was her baby, baby, baby, baby. She has learned to share her baby but she never had to learn to love him.
That came naturally.