Choice in dropdown menu, affects value in otherdropdown menu

Hi

I have a dropdown menu(Type of legend) that should chose a certain
value in another dropdown list(assigned to responsible).

This should proberbly be done on "action on user input".

Though in some cases a third dropdown menu
(Please indicate the assigned person) should overrule the
(Type of legend) and suggest another value in the dropdown menu
(assigned to responsible).

Can you help me on this.

It is my appl. "AFB System" form QC System"

BR Skouboe

N.B. If it is easier for you we could take a meeting about this!