Can grandparents or other relatives be declared additional legal parents under Ontario's multi-parent provisions?

In principle, Ontario's multi-parent provisions are not limited to a specific list of relationships — what matters is whether the adults involved entered into a qualifying written agreement before conception identifying who is intended to be a legal parent, up to the small number the legislation allows. In practice, this route is used far more often by couples and known donors involved in assisted reproduction than by grandparents or other relatives, but a relative could potentially be included as an intended parent if they were genuinely part of the conception arrangement and the agreement was properly made beforehand.

Being an involved or supportive grandparent after a child is born, without having been part of a pre-conception agreement, does not on its own create legal parent status — that kind of ongoing relationship is more typically addressed through a contact order rather than a parentage declaration. Anyone considering including a relative as an additional legal parent should get advice early in the planning process, since this depends entirely on documentation and intentions established before conception.