As in any family with children, one child is always the baby of the family. There may be other names for this position within a family---youngest, last etc, but regardless, one is always the baby.
Unless of course, there are no children in the family, then the husband is the baby, ha ha. Kidding. Sort of.
Moving on.
In our family, our second child was the baby for six years before our new baby moved in. And, I believe, like most families, we wondered how it would be with the new baby knocking the current out of his position and taking over.
Any concern we had was completely unnecessary. Our 6 year old was more than happy to move into the "middle child" roll and has filled the big brother shoes in ways we would have never imagined. He has said more times than countable: how much he loves his sister, how wonderful it is to have a sister, how happy he is we got him a sister.
Here are some pictures, the progression is from the first photos we have of them together, to the last. And it's no exaggeration when I say that of all the photos I have with more than one person in them, I have the most of these two....my babies!!
Photo below, after he "pay in leeps" with her, requires it's own post, those leaves in her hair were a nightmare!