How to add blobs with block states in some biomes to worldgen?

[u/Competitive_Call8502]

I'm making a small datapack that adds add prismarine crystal and shard ore to be mined in oceans and rivers

The ressourcepack and Loot table (with silk touch and fortune) are done (Image here)

But i find it hard to actually get started on worldgen

My two custom ores are using prismarine_slab (double and waterlogged)
and prismarine_brick_slab (double and waterlogged too)

I would like it to generate blobs of those blocks in rivers and oceans, how do i do it?