Limit the record entering in grid to Only one at a time in Headerless detail

I am calling a Headerless detail form from another form.

Is there a way in which we can limit the user to enter only one record at a time in the grid ?

and when the next time the user comes back only the next row of the grid should be active and previous record must be displayed but in inactive so that the user can not change it later in stage.

I selected 'No adds on update grid' and wrote 'Insert Grid Row(All rows)' in post dialog initialized. But it is still not displaying a row where I want to enter some info and craete a new record by clicking OK button.