How to attach file to message record?

We need to create message records from the user's local e-mail data and link the record to multiple records in our script.

I thought the following code would work.

record.attach(
record: {
        type: record.Type.MESSAGE,
        id: messageId,
},
      to: {
        type: "file",
        id: fileId,
      },
)

OR

record.attach(
record: {
        type: "file",
        id: fileId,
      },
      to: {
        type: record.Type.MESSAGE,
        id: messageId,
},
)

But we got the following error.

{"type":"error.SuiteScriptError","name":"SSS_INVALID_ATTACH_RECORD_TYPE","message":"Attaching of record type file to is not supported.

{"type":"error.SuiteScriptError","name":"SSS_INVALID_ATTACH_RECORD_TYPE","message":"Attaching of record type message to file is not supported.