Actually it doesn't seem it was required to send them.
This is from the instructions straight from Kansas Department of Revenue:
"The Department of Revenue does not
require that you enclose copies of W-2s or 1099s with Form K-40,
but reserves the right to request them at a later date."
Instructions can be found here
Once you have the instructions for the tax year you need.
You can press Ctrl + F on your keyboard and search "W-2".
The quote above is from the instructions for Line 22.
