Also i added a fiidle explaining the feature. 
http://jsfiddle.net/sundarvms/kso7xjgc/2/

Yeah you got it right.

Actually my model is bigger one. say 20 properties. But my grid shouldn't need to show all. (Grid will have most important 7 columns). For additional details I'm using Detail template to show all properties. 

  In this scenario, I'm allowed to enter 7 properties only in inline and incell. I can achieve my goal in popup mode with custom template. 

   But I feel instead of popup, we can use template mode as well.

Right now, I'm able to achieve this as follows, 
In detail template, I'm having a button for update (not the model one's) and initiate a ajax call.
For add, catch the edit and load the detail template as follows,

  if (e.model.isNew()) {
                e.container.html('<td class="k-hierarchy-cell"><a class="k-icon k-plus" href="#" tabindex="-1"></a></td><td colspan="7">Add a new record &nbsp;&nbsp;&nbsp;&nbsp;<a style="float:right;" class="k-button k-button-icontext k-grid-cancel" href="#"><span class="k-icon k-cancel"></span>Cancel</a></td>');
                var grid = $("#Grid").data("kendoGrid")
                grid.expandRow(grid.tbody.find("tr.k-grid-edit-row").first());
            }