how could dynamicly create fields and add them when needed i am using a repeater

object oTemplate = "c:\\knowittemplate.dot";
                    var wordApp = new Application();
                    var myDoc = wordApp.Documents.Add(ref oTemplate, ref missing, ref missing, ref missing);
                    object doNotSaveChanges = WdSaveOptions.wdDoNotSaveChanges;
                    Range rng = myDoc.Range(ref start1, ref missing);

                    foreach (Field myMergeField in myDoc.Fields)
                    {

                        Range rngFieldCode = myMergeField.Code;

                        String fieldText = rngFieldCode.Text;



                        // ONLY GETTING THE MAILMERGE FIELDS

                        if (fieldText.StartsWith(" MERGEFIELD"))
                        {

                            // THE TEXT COMES IN THE FORMAT OF

                            // MERGEFIELD  MyFieldName  \\* MERGEFORMAT

                            // THIS HAS TO BE EDITED TO GET ONLY THE FIELDNAME "MyFieldName"

                            Int32 endMerge = fieldText.IndexOf("\\", System.StringComparison.Ordinal);

                            Int32 fieldNameLength = fieldText.Length - endMerge;

                            String fieldName = fieldText.Substring(11, endMerge - 11);

                            // GIVES THE FIELDNAMES AS THE USER HAD ENTERED IN .dot FILE
                            const char newLine = (char)11;
                            fieldName = fieldName.Trim();

foreach (var vItem in myDoc.Fields)
                            {
                                if (fieldName == "ASSIGNMENTCOMPNAME")
                                {
                                    vItem.ToString();
                                    // here i want to make add the field when need so it can create multiple field witch this fieldName but i want i to have different value
                                }
                            }