Normally, a person cannot sponsor his brothers or sisters, or other relatives. However, in some cases a person can sponsor a brother or a sister, niece, nephew o even his own grandchildren:
If parents are deceased
the person to be sponsored is under 18 years of age
not married
There are some requirements for both the sponsor and applicant:
The sponsor needs to sign a guardianship agreement with the Canadian Immigration Office
The applicant needs to collect consent from the home country
Other than the orphan family member, one can sponsor another relative: