Prevent Closing Record Form with Client Side Record Add-in

Good morning,

Is it possible to prevent the record form from closing using the ITrimAddin interface?

We're writing an external link to dynamically set mandatory fields on a record entry form based on the value of a UDF. The code works fine and displays a message box to the user to notify them that certain fields are mandatory, but when clicking OK they're presented with a message that saving the record was cancelled by the add-in. Is there a way to simply return the user to the record form when clicking OK?

Here's the code we're calling in the PreSave function:

if(GetFieldValue("RecordStatus", record) == "Submitted")
    foreach (string field in fields)
        if (String.IsNullOrEmpty(GetFieldValue(field, record)))

    string missingFieldsCSV = string.Join(", ", missingFields);

    if(missingFieldsCSV.Length > 0)
        string message = record.Number + " requires the follwing fields to be populated:" + Environment.NewLine + missingFieldsCSV;

        DialogResult dialogResult = MessageBox.Show(message, "Content Manager", MessageBoxButtons.OK);

        return false;