Forms :: Saving Data From Multiple Datablocks Into New Table?

I have a form with 2 datablocks, datablock 1 is the datablock in which I want to write data too that table within the database.

datablock 1(which i want to insert data too) is:

In forms layout this simply consist of a display box at the top of the screen which is populated by a LOV from another table within the database. The lov value selected will then be placed in the appropriate field of the table. For example the LOV contains a list of every single car make there is. i.e. Renault, Ford, Vauxhall etc

datablock 2 (in which i just want to read data from, and write the data to the table used in datablock1) is:

Below this is my second datablock, which on the trigger 'on-new-form-instance' reads data from an already existing table and displays a list of every single make of car ie, focus, clio, megane, astra etc (tabular layout displaying 12 records at a time). Beside these car models will be a checkbox which is a non database item, originally unticked.

What I want to do is the user selects a car type from the top LOV say Renault for example, then they will go down the list of car models checking each and every model of car Renault makes, i.e clio, megane, etc when these models are all checked, and the user clicks save, it will insert into my table (which is the top datablock) the car which was selected From the LOV at the top, plus each and every car model which has a checkbox checked. So for example, say the user selects Renault from the top LOV and checks models clio, megane, laguna. There should be 3 entries in the table consisting of:

Renault, clio
Renault, Megane
Renault, Laguna

Now I have got it to work partially, in the fact that if I load the screen, select my car type and then multiple models that it will add 1 car type and model to the database but not the others which I have checked. I think I need it to go down each row and check if the value is ticked or something like that? using row id or something?

Here is the code I have so far: Just so you know car_model is the name of my table used as my second datablock, contains all car models as u would expect.

BEGIN
if :model_chkbox = 'Y'THEN
v_model_id := :car_model.id;
INSERT INTO NOTE_ACCESS_DEFAULT (car_type, model_id)
VALUES (:car_type, v_model_id);
end if;
EXCEPTION
WHEN OTHERS THEN
MESSAGE('SQLERRM: ' || SQLERRM);
END;

Another option was to do a loop and go through each record and see if it is checked, not sure how I would implement this but it does seem like a very inefficient way to do such a task, perhaps it would be something to do with when a checkbox is ticked stamp it or something.