Adding Fields to an Inquiry Form from an existing Data Class

Good day all,

How can I add a new field from the same data class to the records or what would be the best way to add a new field to an Inquiry screen form a pre-existing data class?

For exampe:

On the IN407000 screen (Inventory Lot/Serial History) in the Records grid, there are multiple fields with links to diffrent data classes.

CustomerI Fields Data Class = PX.Objects.AR.Customer

Any links to docuemnts, examples would be great. 

Thanks so much