To the guests and the rest of the Harem, the blood Christening was to bless the children in the ways of the Lilin and assure they were fully loved. That is true, but the blood that had been let out had been with special spells and potions that once touched against the five babies and the Emperor and the Empress it have a full map of their genetic code on who the babies had gotten their gene codes from, despite growing inside whoever they ended up in.