I was directed to a parable (again I think it was Taoist) that was supposed to parallel the parable of the sower. Apart from both texts using agricultural imagery I couldn't see the resemblance.
I think that's how it's going to be. The material Jesus or his ghost writers are supposed to have plagiarised is all going to turn out to be not very similar and/or of a later date- so that it's more likely the writers were cribbing from the New Testament.
Of course the New Testament cannibalises a lot of Jewish scripture- both canonical and apochryphal. Of course it does. But there's nothing dishonest in that. The earliest readers would have recognised and approved the borrowings. The writer's whole point is to show how Jesus fulfilled the Law and the Prophets.
I was expecting my researches would undermine the uniqueness of the Christian scriptures. What has happened is the reverse. They have brought home to me just how new and fresh the gospels are.