Convert string to object&Arrary

Are you trying to fit all of the rows from the input into the $Worker_Reference.ID array? Like so:

{
    Worker_Reference: {
        ID: [
            { type: "Employee_ID", value: "A4" },
            { type: "Employee_ID", value: "A3" },
            { type: "Employee_ID", value: "A2" },
            { type: "Employee_ID", value: "A9" }
        ]
}

Or, is every row still a separate document, like so:

// Document #1
{
    Worker_Reference: {
        ID: [
            { type: "Employee_ID", value: "A4" }
        ]
}

// Document #2
{
    Worker_Reference: {
        ID: [
            { type: "Employee_ID", value: "A3" }
        ]
}

// ...

And, where does the $Provisioning_Group value fit in?