[@Wick]

Non-canon means that it never happened in the books. Our characters are not direct descendants of book characters. I could get behind the McGonagall one (McGonogall did have nieces and nephews that were never named). However, Miriam Yaxley never existed, so Rabastan Lestrange would never have had an affair with her. Can you perhaps make him a descendant of a non-canon pureblood family? Or, perhaps still his mother was Miriam Yaxley and his father was another pureblood never named?