Here is a very simple blueprint node setup for spawning multiple different meshes in instanced static meshes from a single blueprint you can extend this setup indefinitely to include randomization and uniform options and so on! Also included a very nice node called the 2D Grid Spawn Macro that we highly recommend! You can use that instead of the last For Loop if you want to spawn objects in a more uniform grid, but you can randomize that aswell with simple random range float add/multiply/subtract for the Poly Center Output before you set the add instance transform.

Prop HISMs array is an array of Hierarchical Instanced Static Mesh Component – Object References

Prop Meshes is an exposed variable of Static Mesh – Object References. When you add an array item here, the blueprint will create the necessary HISM component for that mesh and store it to the Prop HISMs array variable, then add an instance to each instanced mesh type at random.

Enjoy!