How to resolve graphql relationship error

After updating my project, when I tried amplify push I got the error below
Song must have a relationship with Post in order to use @belongsTo. from my graphql schema code.
What can I add to create the relationship to connect Song to Post? Because I am lost, I don’t know what else to do because all my efforts did not work, and I am still getting the same error.
Here’s my graphql schema code:

type User @model {
  id: ID!
  username: String!
  email: String!
  posts: [Post] @hasMany(indexName: "byUser", fields: ["id"])
}

type Post @model {
  id: ID! @index(name: "byUser", sortKeyFields: ["userID"])
  videoUri: String!
  description: String!

  userID: ID!
  user: User @belongsTo(fields: ["userID"])

  songID: ID!
  song: Song @belongsTo(fields: ["songID"])
  
}

type Song @model @auth(rules: [{ allow: public, operations: [read] }, { allow: owner }]) {
  id: ID! 
  name: String!
  imageUri: String
}