How to import a schema.prisma file inside another?

One of my schema.prisma's file is wrote like this:

generator client {
  provider = "prisma-client-js"
  output   = "./generated/own_database"
}

datasource db {
  provider = "postgresql"
  url      = env("DATABASE_URL")
}

model Employee {
  ...
}

And I have another one, which is like this:

generator client {
    provider = "prisma-client-js"
    output   = "./generated/another_database"
}

datasource db {
    provider = "postgresql"
    url      = env("DATABASE_URL_2")
}

model Costs {
    cod_center_cost Int      @id
    description String?  @db.VarChar(100)
    status           Boolean?
    classification Int?
}

...

I have a model that needs to have a relation to another model, but how can I refer an another file's model?