Family/ adoption questionn.?

I am adopted and so is my brother. My brother is actually younger than me, and he has got to meet his biological parents and family. He does have a sibling. A sister. Techinally by blood you are not related, but by law you are! He is your brother his family is yours just like your family his. So if he is to have more sisters or brothers they are yours as well. I would just relax doesnt sound like your brother would think of you any different if he did have more siblings. :) Just think if he does a bigger family!