Save and Edit Form with Gridview

Question

I have two gridview in my form with other Text Box and Other controls for getting input.

 

I have only one save button for inserting data at first time and update data if exists(Using Sql stored procedure).

 

I want gridview to be in edit mode if records exits. I had separate buttons for add new row for gridview.

 

User can edit gridview data and can insert new row also with save button outside gridview.

 

Im not using inbuilt edit/update buttons in gridview.

 

Kindly give a suggestion to achieve this.

Thanks in advance.