Got this from another forum and it might be of help to someone else.
If your spouse or common-law partner, children 16 years of age or older, or any other individuals whose information could be contained in the requested records wishes to release their information to the designated representative, they must sign in the space provided. Information about minors will only be released with the consent from both parents or a valid Canadian court order indicating that the applicant is permitted to obtain their information. Obtaining consent from all parties will permit Immigration, Refugees and Citizenship Canada (IRCC) to release their information and will provide you with more information in response to your request.
INSTRUCTIONS FOR THE ATIP CONSENT FORM
Submitting a properly completed consent form with your request helps to prevent delays.
Simple two-step process
Section 1 - Provide information about the requester.
Section 2 - Provide details about whose information is being requested (i.e. family members, spouse, children).
Up to four people can be included on a single form.
Consent valid for 1 year
The same consent form can be submitted with each new ATIP request.
Requirements
Consent for children under 16
Both parents have to approve the release of their children's info (under 16). Provide the minor's information in section 2. They are not required to sign the form.
• ensure this form is signed by both parents OR
• submit separate forms for each parent, listing the minor's information on each form OR
• submit a signed form from one parent, and a valid Canadian court order (proof of custody)
Signature + Date
To safeguard against fraudulent forms, only original signatures signed in BLUE will be accepted. No electronic signatures. Make sure the applicant includes the date of the signature.
Scanning tips if you submit online
A colour scan in good resolution (300 dpi and up) OR taking a close well-lit snapshot of the form with your smartphone camera will help ensure your form is accepted.
https://www.canada.ca/content/dam/ircc/migration/ircc/english/pdf/kits/forms/imm5744e.pdf
It's a lot clearer now.