can anybody help please?

can anybody help please?

i have a drop down of companies i.e (kipg-1,kipg-2,kipg-3,kipg-4) and i have used onchange event to access the id of companies.
and i have a textbox which will always be opened when trademark is selected.

question is


if user type something in textbox it should show a list of trademark of kipg-1,kipg-2 respectively.but this can only be done when id of selected company is passed in keyup even. how to do that?

thanks in advance