What is the authority structure and the local variations in actual practice governing how ashes from cremation should be kept for Catholics?

This *Simply Catholic* article [Catholic Burial and Cremation](https://www.simplycatholic.com/catholic-burial-and-cremation/) explains the **rationale** behind the prohibition of spreading the ashes from a cremated person, along with the **precondition** that the cremated person needs to believe in the resurrection of the body. Instead, the ashes are to be buried or stored in a sacred place to encourage prayer on behalf of the deceased as a member of the communion of saints. The basis for the article is the 2016 instruction from the Vatican's CDF. My question has to do with the *authority structure* and the consequent variations of **local implementation** of this teaching: - how much of the rules is set in canon law, how much by CDF, how much is set by a country's congregation of bishops (like USCCB) - whether bishops or even priests can relax or add further restrictions in connection with preserving the ashes - how much of the actual practice varies by country / diocese