Can a parent add their own surname to a child's name without the other parent's consent?

No, not through a standard application — adding a parent's surname to a child's existing name is still a change to the child's legal name under the Change of Name Act, and it generally requires the consent of everyone with decision-making responsibility or parenting time for the child, the same as any other change to a child's surname. A parent who wants to add their own name, whether to replace the child's existing surname or to create a hyphenated combination, cannot bypass the other parent's consent simply because the change feels partial or symbolic rather than a full replacement.

If the other parent won't agree, the parent seeking the addition would need to ask a court to dispense with consent or resolve the issue as part of a parenting application, where a judge would apply the best-interests-of-the-child test to decide whether the change should happen despite the objection. Parents in this situation should not assume that a smaller or partial change is treated more leniently than a full name change.