Terrain Material (Multiple textures support)

Hello

I create random terrain, at runtime, based on seed, with RuntimeMeshComponent. This generation work.
But now, i need to apply a material on it, with multiple textures, for different biome/region.

My knowledge in material is limited so, i dont know how to achieve this.
For now, i dont really generate biome, (cause, i dont know the best way to do that), i just put a random number (between 0 and 6) in green vertex color channel.

I can Lerp between two textures based on Green Channel number,
but Alpha is only 0-1. So, i guess it’s not the good way
Maybe i miss other parameter editable in code (with SetParameterValue ?) for pass my data…

The question is how to (if possible) use custom data in material for select right texture ? What is the way ?
Sorry for noobness and my english :smiley: