I'm trying to send email to multiple recipients using a REST API call

Question

When I use the messageDefinitionSends/.../sendBatch API call, that I learned about on Stack Exchange, to send email to multiple recipients, email is only sent to the last recipient on the list and only data for the last recipient is logged into the data extension. I know that this API call is not supported by Marketing Cloud, but does anyone know if this call actually works? Any suggestions would be appreciated. Thanks.

Here is the API call and the payload I used:

POST https://EndPoint.rest.marketingcloudapis.com/messaging/v1/messageDefinitionSends/key:{KeyValue}/sendBatch

[{
"To": {
    "Address": "[email protected]",
    "SubscriberKey": "[email protected]",
      "ContactAttributes": {
        "SubscriberAttributes": {
            "BorrowerFirstName": "John"
       }
      }
    },
"To": {
    "Address": "[email protected]",
    "SubscriberKey": "[email protected]",
      "ContactAttributes": {
        "SubscriberAttributes": {
            "BorrowerFirstName": "Jim"
       }
      }
    },
    "Options": {
    "RequestType": "ASYNC"
}
}]