Custom Line Items/Group in a Custom Module, How?

I’ve only managed to make 4 customs fields so far:
quantity, product, status(dropdown), and the line field of type function.
Inside the line field, I have put this in the include attribute: custom/modules/AOS_Products_Quotes/Line_Items.php

I extended the AOS_Products_Quotes module so I can edit the Line_item.php and the line_item.js

I have been meddling with these two files for some hours now and I am very at what to remove or where to add my custom fields.

My goal was to have a line group in my custom module. I only want to have Quantity, Product and Status dropdown fields whenver I add a new line. Ive only managed to deleted the stuff thats beside the line(the one where it calculate the total)

Any help is appreciated…

Check this post for some ideas: