diff --git a/js/relation-select.js b/js/relation-select.js
index 5a5ee6e..01bc6bf 100644
--- a/js/relation-select.js
+++ b/js/relation-select.js
@@ -196,16 +196,26 @@
         return $('input', relationSelectItems[id]['element']).length + 1;
       }
 
+      function getNextDelta(id) {
+        var delta = countArity(id);
+        // Get the next available delta.
+        while ($('input[name="field_rel_products[und][0][endpoints][' + delta + ']"]')) {
+          delta++;
+        }
+        return delta;
+      }
+
       /**
        * Create an input
        */
       function addInput($row, id, entitydata){
+        $delta = getNextDelta(id);
         // Create a hidden input to mark the new item being selected
         $input = $('<div class="rs-wrapper" />');
         $input.append($('<input type="hidden" value="' + entitydata
             + '" name="'
             + relationSelectItems[id]['element'].attr("data-field-name")
-            + '[]" />'));
+            + '['+$delta+']" />'));
         $input.append(themeValue($row, entitydata));
         addInputRemoveLink($input);
         relationSelectItems[id]['element'].append($input);