Client script for Customer quick-entry form?

ERPNext 13.28.0

I’m trying to customise the “new customer” form with a client script. When a new customer is being created, ERPNext initally presents a “quick-entry” form and in fact this contains all the fields we will need for most customers so we expect to use only the quick-entry form most of the time. However, we would like to add a connection to a postcode lookup service we use, which provides us with some Javascript code to access the service, in order to populate the address fields on the form. I have already incorporated this code successfully into a client script for the Address form and it works well.

I want to add it also to the Customer quick-entry form. I can create a Customer client script but it only runs when the full-size Customer form is displayed.
I can see that the quick-entry form fields are defined in customer_quick_entry.js and perhaps I could add some code there but I am sure that file would be overwritten on each bench update so I would prefer to define a custom client script.

Is there a way to create a script to apply to the quick-entry form or do I need to do it another way, for example by creating an app?

Perhaps my original question was too verbose and not clear enough. I’ll try to make it brief and clear:
How can I apply a client script to a “quick-entry” form? When I write a script for a doctype that has a “quick-entry” form and then create a new instance of the doctype, the script does not run when the “quick-entry” form appears. It only runs if I edit the document in the full-page form.
Is it possible?

Hi BillJ,

Client scripts don’t work with the quick entry form. It’s a completely different form of architecture. There are a few different hacks that people have implemented at various points, but I’m not aware of anything that works smoothly.

Thanks, Peter.
I’m quite new to ERPNext and have spent the last couple of months setting it up for my business so I’ve picked up some things about the architecture but still have more gaps than knowledge. Perhaps I’ll just have to hack the quick-entry form and pay attention to it on each upgrade. I only need to add one specific feature to it so maybe I can come up with a simple hack that works smoothly enough.
I’ll search around to see how others have done similar things.