My suggestion is to subscribe to a genealogical research site, e.g. Ancestry; Genes Reunited; My Family, to get the information that you have been asked for. The more information that you can provide, the greater will be your chance of success, and the less time you will spend in being pushed from pillar to post. A look through the birth and death records of a suitable website will tell you what you want to know. I used Genes Reunited to find a sister who was born and died before I was born. All I had to go on was a brief mention by my mother when I was about 11 years old. I had no written records of my sister at all, but I found her records in a fairly short time. So you could be lucky also. Best of luck.