You should add his information. As far as i know, all of family passports are basically attached with each other.
Better not to hide anything.
Under any circumstances you should noy hide, otherwise it would affect your case adversely.
Its better to be assessed with true information, rather than assessed with false/ incomplete information.
IRCC have rights to make you 'inadmissible', if they feel that something is hidden by applicant.
I've seen cases, where not mentioning about previous refusal in the application, leads to another refusal and even 'inadmissibility' to their country either for few years or for lifetime.