The only way I know is to turn off the ability to insert in the control properties, But then I do not think your add button would work.
I have seen where you display a table of data and have a row button which pulls the info from the row into another section(an Edit Area). The user modifies it and then hits another button to write it back. Adds could be handled that way, with code, but it makes it more complex because you cannot use the stock functionality. But it does give you more control over the UI.