We’ve been very successful in transitioning our one-child home to four children. I think this article sums up why we haven’t had any large scale birth order issues. Because Little One is only three, and she is going from an only child and oldest child to the baby is helpful. She didn’t have any control over being an oldest because she never had a younger sibling. She is three and exerts her three-ness independence so our six year old, who is used to being the baby, gets babied more because our toddler could care less about being babied.
We did not displace the oldest child that we are adopting. She is almost ten and very much an oldest child. She is mothering and bossy, which we’ve been promoting in positive ways. Displacing her would take away a big chunk of her self-worth and personality.
Because we now have four individuals there is less emphasis on birth order and more emphasis just on getting attention period. There is no middle child also, which helps. The children regularly switch their play partners, there are no cliques or ganging up on one person.