Combine 2 blockstates

Hey so I downloaded a pizza resourcepack, but the problem is that it replaces the cake rather than adds a pizza. I think here would be the issue I need to solve, in the assets/minecraft/blockstates but I'm not too sure on how to combine these so I can have both in the game.
cake.json
{
  "variants": {
    "bites=0": {
      "model": "minecraft:block/cake"
    },
    "bites=1": {
      "model": "minecraft:block/cake_slice1"
    },
    "bites=2": {
      "model": "minecraft:block/cake_slice2"
    },
    "bites=3": {
      "model": "minecraft:block/cake_slice3"
    },
    "bites=4": {
      "model": "minecraft:block/cake_slice4"
    },
    "bites=5": {
      "model": "minecraft:block/cake_slice5"
    },
    "bites=6": {
      "model": "minecraft:block/cake_slice6"
    }
  }
}

cake.json
{
    "variants": {
        "bites=0": { "model": "oxywire/pizza_6" },
        "bites=1": { "model": "oxywire/pizza_5" },
        "bites=2": { "model": "oxywire/pizza_4" },
        "bites=3": { "model": "oxywire/pizza_3" },
        "bites=4": { "model": "oxywire/pizza_2" },
        "bites=5": { "model": "oxywire/pizza_1" },
        "bites=6": { "model": "oxywire/pizza_0" }
    }
}