Avoid Creation of relatonship depending upon condition

hiii i want to avoid creation of relationship depending upon condition that same item cannot be added in relationship i write code to find same item but not able to avoid adding selected item in relationship i put code on onInsertRow event of relationship grid

var rowId = gridApplet.getSelectedId();
var rid=relatedID;

alert(rid);
alert(relationshipID);

var thisItem1 = parent.thisItem;
innovator = parent.thisItem.getInnovator();
var bid=thisItem1.getProperty("id");

var imnf=innovator.newItem("bal_batch2process","get");
imnf.setProperty("related_id",rid);
imnf.setProperty("source_id",bid);
var res=imnf.apply();
var mnfCnt=res.getItemCount();
if(mnfCnt!==0)
{
  alert("Mnf Process used already");
  gridApplet.deleteRow(relationshipID);
  var no=gridApplet.getRowsNum();
  alert(no);
  var gid=gridApplet.getRowId(no+1);
  alert(gid);
  gridApplet.deleteRow(gid);
  //gridApplet.deleteSelectedItem();
  // gridApplet.removeAllRows();
  return this;
}