Sugarcrm 7.9: Trying to extend core field

Hi,

I am trying to extend `modules/Products/clients/base/fields/quote-data-relate/quote-data-relate.js` i can make modification to the core filed to add my functionality. I would like to know how can i extend the core field in to custom so i can use it even if in future sugar change the core field. 

I also tried to copy the field `quote-data-relate` related files to custom folder and editing it but its didnt work for me. Any help pls.