Block Drops

I'm trying to make a pack where when mining any ore it drops the respective stone as well.
Big problem though is when mining it with silk touch it also drops the stone of the ore type.
I'm unsure how I'd get this to work. I am using 1.21.1 which I know is an older version but I'd like to create it from that version and then update it to later versions.
Below is what I've currently got setup:
{
  "type": "minecraft:block",
  "pools": [
    {
      "bonus_rolls": 0.0,
      "entries": [
        {
          "type": "minecraft:alternatives",
          "children": [
            {
              "type": "minecraft:item",
              "conditions": [
                {
                  "condition": "minecraft:match_tool",
                  "predicate": {
                    "predicates": {
                      "minecraft:enchantments": [
                        {
                          "enchantments": "minecraft:silk_touch",
                          "levels": {
                            "min": 1
                          }
                        }
                      ]
                    }
                  }
                }
              ],
              "name": "minecraft:coal_ore"
            },
            {
              "type": "minecraft:item",
              "functions": [
                {
                  "enchantment": "minecraft:fortune",
                  "formula": "minecraft:ore_drops",
                  "function": "minecraft:apply_bonus"
                },
                {
                  "function": "minecraft:explosion_decay"
                }
              ],
              "name": "minecraft:coal"
            }
          ]
        }
      ],
      "rolls": 1.0
    },
    {
      "bonus_rolls": 0.0,
      "entries": [
        {
          "type": "minecraft:item",
          "name": "minecraft:cobblestone"
        }
      ],
      "rolls": 1.0
    }
  ],
  "random_sequence": "minecraft:blocks/coal_ore"
}