How to auto generate a dropdown selection from another dropdown field selection?

[Kaysie34469230y2n5]

Greetings all,

Happy new year.

I have an "employer" dropdown list (each item generating its value being the address), but I want whichever item selected, to output the selection of my "carrier" dropdown list (where each carrier item has its own value being the address). 

I am puzzled on whether I use a custom keyscript or a custom code? Many thanks for your help

[Eugene Tyson]

I'm not sure what you're asking here - it's not entirely clear what your start point is, what your goal is, what methods you're using, what software or indeed what you're asking here in general.

Can you please be more specific in your workflow and the issues you're facing?