Generating two Features reliably in the same place

I'm trying to create a large ore vein that spawns underground with an indicator on the surface. My idea was to have an ore_spots feature that spawns with an ore feature below it. I thought there would be some kind of "compound" type for Placed Features, but I didn't find one. Is there a way to abuse the pseudo-randomness of worldgen to have these two features always spawn in the same chunk, square-d the same way? I know there's this one exploit players use to find diamonds based on clay patches. I want to replicate that intentionally.