Sugarcrm 7.9: Validate Quote `Group List` upon Save

Im trying to add validation to Quote line items. As the quote moved to  Sidecar in Sugarcrm 7.9 save to lineitems are difference. We can edit and save each lineitems. 

Im trying to validate some field upon save in the Line items refer image below.

I have checked the architecture of Quote module in http://support.sugarcrm.com/Documentation/Sugar_Developer/Sugar_Developer_Guide_7.9/Architecture/Quotes/ 

But i couldn't find any supporting document to add validation upon submitting after edit. I have checked how sugar does the save for each row in `quote-data-editablelistbutton`  by extending `BaseEditablelistbuttonField`. How can we extend the `BaseEditablelistbuttonField` and add validation to it. REF:

crm/src/modules/Products/clients/base/fields/quote-data-editablelistbutton/quote-data-editablelistbutton.js

Note: I have tried to extend. But when i copy the `quote-data-editablelistbutton.js` and place the entire field in our custom i can able to do it. But i am looking for a solution when i can just extend the file so i can add my validations to line items.

Also have a look at Add field in QLI within Quote detail/edit view 

Thanks for the helping in advance.