Both Demon's Souls and Bloodborne were co-productions with Japan Studio, and neither game would've been possible without them. Especially Bloodborne since they were the ones who began the collaboration with it's concept in mind. Demon's Souls began as a very different game before Miyazaki was brought on and changed the gameplay to be what it is, but artistically it's mostly Japan Studio. That's why there are many difference between Japan Studio-led "Souls" and independent From "Souls".
It was Sony's idea to collaborate with Miyazaki, but he came up with the idea of Bloodborne by himself. Demon's Souls was a different game already inside FromSoftware's studio and it was a disaster, but that story is known to everybody interested in their games, not going to repeat it. You're either misinformed, or trying to rid FS of agency on creating their games. I won't deny that Sony Studio Japan affected their games, but saying that they come up with Demon's Souls or Bloodborne, or that their artistic input is at least 50%, yet alone more than FS's, is ridiculous. Both games were developed in house in FS's studio from the early concepts to the final release.