Yeah these buybacks are making it confusing. I was under the impression though that they should be listed under the set they were originally pulled from. I figured out how to add a checklist (new at doing that) and I went ahead and added the 2017 Rediscover Topps Stamped Buybacks to the 2017 Heritage set.
Would you mind deleting the Pat Borders you added for me on the 2017 Topps set? I don't think I have the permissions for that one.
I would think this is the best way to do it for now until admin or whoever says otherwise.