This is all very possible, albeit it could be how Phillip died. When he was younger.
From the preview, you see a child falling down a well. Theoretically, lets assume that's Philip, and that he died as a child, but was revived with the power of the Gaia Library.
Also, from the way Philip's eyes widened when he was reading a book, I'd say he's made quite a discovery.....about himself.
Maybe that's why Ryubei was experimenting with Raito, because he no longer considered him his son, because his "true" son died in the well.