Select DropBox and update Other...

Hi, my english is bad :(

I have two forms Clients and Works...

I post all my clients in the CLIENT FORM whit several fields (address, phone, blabla):

Fields Importants:
DNI (unique number of client)
First Name and Last Name (string)

And in the WORK FORM:

I charge the work (not important now) maked a each user. But Selecting the Field Type DNI: "Import Data" DNI of the CLIENT FORM and First Name and Last Name of CLIENT FORM also...

I need to a Script when I select in WORKS FORM a DNI (see images), select the First Name and Last Name of this DNI

automatic.

Thanks...