Sibling group adoption refers to the adoption of multiple children that are biologically related to one another. Unless adopted internationally, sibling group adoptions are handled by public agencies. Siblings are difficult to place. They're more expensive to care for, require more time and will also need more space in a home than if just one child was adopted. For the most part, public agencies try to not split siblings up during the adoption process. Some even provide health and dental insurance for the children as incentive to place them in adoptive homes.
Because sibling sets are so much work, they are usually adopted by older couples that have already raised children and want to raise more without having to start with an infant again. The adoption of siblings is beneficial for the children because they will still get to grow up with someone biologically related to them and generally adapt better to new homes if they're doing it with a sibling.
International adoption agencies also push for sibling or "twin" adoptions. And, when you think about it, this can make sense financially and socially. Adopting siblings is financially smart because it saves the adopter from having to make a second trip if he or she chooses to adopt internationally again in the future. And, it makes sense socially because the two children will have each other to identify with as they mature.
All about Sibling Group Adoption. Find resources and information about Sibling Group Adoption from adoption.org. http://www.adoption.org/adopt/sibling-group-adoption.php. Adopting Sibling Groups - Child Welfare Information Gateway.