Lucifer trembles at the task father there is no way this world can survive alone hmm what do I do … Wit that is it what if I combine this world with another world and accept to serve a different God …. That's it Now to send the Message.
Across the multiverse Lucifer of ( Beginning of the end ) Receives the Message and sends a message back
'' If you surrender to Me you should know this world I have been remade to replace God and Grandfather won't allow your God to take his place so instead if your father either surrenders his powers to me or agrees to my plan of him and his sister being power source for Heaven and Hell when I take over meaning God will be Heaven and the Darkness will be Hell actually another plan God and combine with me and The darkness combing with herself''.
Lucifer of this world receive the message and froze in shock then sent the message to his father and Aunt who surprisingly agree to the other Lucifer Second plan allow as they can do more then just be a plane.
When Lucifer of Beginning of the end got that he sent back the message that he would make different planes of the afterlife and the homes of the gods and they can serve as the homes of both while also being Beings called the Power that be from Buffy that his father made real but they are tasked with keeping them under my rule … Maybe send the darkness sends her consciousness to herself and God allows Lucifer to turn him into a archangel with 80% of his power become Amenadiel the Wrath of God and Angel of Time and Death
God and The darkness agree with the idea and it was set
The two do the ritual and this world was added to Lucifer's and he put it in a alternate universe that will connect the moment God of this world is unable to stop him