A co-applicant for a Loan is generally a Family Member or a Co–Property Owner.
The following co-applicant combinations in case of a family are the most accepted by the Lenders:
A son or daughter can co-sign a loan for their parents
A pair of brothers can co-sign a loan
A married couple can co-sign a loan
A minor or a friend, who is not a joint property holder cannot be a co-applicant.