If I use a dummy url then I get an error. I actually created a workaround:

In the beforeSubmit event for the add/edit form I created a function which adds or edits the data manually in the grid and then hides the edit form div. I then return false to stop the form from requesting the service. Now anytime I need to add or edit I just show the div before calling the add or edit method for the grid.

This works without any problems that I know of but it would be nice if there was a option for the grid that I could set which would make this much cleaner and simpler.

Thanks for your help.

If I set the editurl to 'clientArray' I receive the following error when trying to add or edit a record using the form:

error Status: 'Method Not Allowed'. Error code: 405