In the Lords time and when more details are known or revealed - he will be sealed to both a Father and a Mother. The sealing ordinance only has significance and full meaning when child is sealed to both a Father and Mother. Every person will have that opportunity and blessing in the Lords time.
In some cases the Father or Mother to whom the child ends up being sealed - may not be the biological father/mother.
NO, a child cannot be sealed to just one parent.