Pull values from parent objects into child objects

I'd like to be able to pull values from Parent objects into number and text fields on forms, as default values, but have them modifiable.

A use case would be a default price for a product/service, so when recording a sale of that product (child object), a default price populates the sales form based on data of the product/service (parent object). But this field should still be modifiable. It would be extremely useful. Thank you!