Where can I find my little brother?

I have a little brother, and I haven't seen him since I was 9 and and he was 2. I don't know if he knows I exist, but i want to find him. He lives with his mother, Marcia Mercer (or Marcia Writh). He also lives with his sister, Johnna, and brother, Brandon. Their last names are either Writh or Mercer. My brother's name is Kohl. His last name is either Wallace or Mercer. I think they live in Nebraska, but I'm not sure. if anyone can help me find them, or know how I can help them, please help! This is all the information I could find within my family. Thank you!!