Searching for my brother, Chicago, 1954

I was born and adopted in Wisconsin. I found my birthfamily in 1997 because the laws in Wisconsin changed and allowed it due to the fact that my birthmother had passed longer than a year after my search.My brother was born in Chicago in 1954. My aunt was 9 at the time and remembers the date, the name he was born under, and that it was Chicago. She had gone with my birthmother and another older aunt to Chicago so my birhmother could avoid a very violent situation with her boyfriend who was not the baby's father.I have been in contact with a person in Illinois name Melisha who contacted me about 5 years ago and I re-contacted her last year. She is very willing to help me try to find my brother. She said I need my identifying information and my birthmother's death certificate. Luckily one of my sisters is willing to see if she can get it for me. She says with this information, I can go through the confidential intermediary system. My oldest sister does not want me to search and is giving me no papers, information, or help. She said it was some kind of promise to my birthmother not to search for either of us. She said the reason why she even called me after receiving my letter is that "everyone" knew about me, but not him. She said something curious though. She said that his birth certificate had no name, only a number. She also said that he was never told he was adopted. That leads me to believe that either she is not telling the truth or that my birthmother knew who adopted him.Can I go through the intermediary system, being the adopted sibling of an adoptee? Melisha says yes, and she has asked for no money.Is this an option for me? Colleen, I have watched your posts for years. I have been amazed at your accuracy, completness, and compassion. It is very refreshing in this day and age of people not wanting us adoptees to know about our "other families" or even look.Lisa Monahan