Storing Document - AutoIndexing fields based on another already filled field

Hello, 

I have a problem when I store document.
I'm filling many fields from Invoice, but some of the fields I would like to fill based on previous entires

When I fill VAT No. of company then city, postal code, name of company, code of this company should be inserted automaticaly.
There is no need to fill them every time I have this company, cause they are constant. Not changable

How I can do this ?

Dear Marek Behnke! It looks like the Community cannot answer your question. Thats why we have opened a Support Request with the Number SR-118378-J3D6X for you. A Software Support Specialist will contact you directly to follow up. We will update this thread with the solution as soon as we have solved the Support Request. With Best Regards, DocuWare Support Team