I am trying to keep track of orders that need to be refunded using a form. 

I would like to keep other employees from entering duplicate records. To accomplish this I would like to have a warning message come up next to the actual field saying "this order already has a refund on it..etc".

I know that Zoho has an "allow duplicate entry" field BUT this displays only after the form has been submitted. I would like to code it where it shows up as soon as it is entered. 

That is one option.

Option #2, which would save my employees time, would be to have the form automatically load with all of the information needed and update only the parts of the forms needed to be updated and NOT create a new record. 

I know that you can have a "Lookup" field that links to the other form - but not the same form you are entering in. Also it does not allow for a manual entry. It only allows for selections by way of checks, radios, or dropdowns. It would not be helpful to have any of these options as we have over 100000 orders on file.

Any help would be greatly appreciated!