We had bio sons ages 4 and 9 when we adopted a five year old daughter. Other than the jealousy over her getting so much attention when she came to the family it seemed fine all around. The boys had a sister.
When they were 11, 12, and 16 I got pregnant and we added another bio boy to the family. All seemed equally happy about their little brother.
My daughter was not interested in meeting her birth relatives at all until she was 21 and since then it has been a strain because she pretty much has abandoned all of her adoptive relatives and that has been the hardest situation to deal with. Growing up? Growing pains for all four, but this disconnection has been just plain painful. Her brothers are kind of angry with her for not acting like she wants to be part of their lives. She is part of her half bio siblings' lives, the ones she found when we helped her reunite.
Good luck. Just being honest.
HUGS