A mix. While siblings can't be directly sponsored, there are specific circumstances where they can be. For security checks, if your sibling's name has hits, they may do extra checks on you.I am trying to understand the main purpose of listing all the immediate family members.
1. Is it due to the possibility of sponsoring them in future once the applicant moves to Canada? Or to perform security checks?!
2. What is the impact if someone doesn’t list them all (like half brothers/half sisters,,etc)? Other than you can not sponsor them?!
3. If somebody has half brother who hasn’t seen him ever and has no clue if he still alive or not. / no contact, does it really matter mentioning him or her?!
Not listing them when you know about them is misrepresentation. Just list what you know about your brother and explain on a separate sheet that you have no contact. It won't affect your app.