While Elsbeth has an outstanding fic, and I wish it were possible to continue or finish it, I don't think it is the one you want. But do make sure you read it. Then go to fanfiction.net look for books, then harry potter, and check out their search tool. I read there a lot, and your plot summary fired up the synapses to recall your summary. Can't remember the name or author, but that plotline is there. Not sure if she's Alya Black in it. You may be crossing the plotlines and names.... Edit ...... Just to clarify ..... Season of change has most of the last segment of your suspected plot. But the goblins were not involved in the change. That came about after the fight in the ministry. The first segment with the goblins helping out is a different storyline and i have not clocked it yet. There have been a few where the goblins did this procedure with similar results.