If the power of the target creature cards changes while in your graveyard, most likely because one has a characteristic-defining ability that defines a * in its power, the total power of the creature cards may become greater than 10. If this happens, the entire selection of targets is illegal. In this case, Reunion of the House won’t resolve and none of its effects will happen. Nothing will be returned to the battlefield, and Reunion of the House will be put into its owner’s graveyard.